Terminal does not use .bashrc variables, but recognized them

Question

I have installed the latest Pop!_OS version on my new computer and wanted to set the following environment variables:

CC=/usr/bin/clang
CXX=/usr/bin/clang++
CMAKE_GENERATOR=Ninja

Instead of typing export CC=/usr/bin/clang each time I open a new terminal, I added these variables to the end of my .bashrc in my home folder (~/.bashrc). When I now type the command echo $CC, the result I get is the expected result "/usr/bin/clang". Same goes for echo $CXX and echo $CMAKE_GENERATOR.

When I now run CMAKE however, I do not get a build.ninja file. Only when I type export CMAKE_GENERATOR=Ninja in my terminal does CMAKE generate a build.ninja file. I am confused by this behaviour.

I am not sure why echo $CMAKE_GENERATOR prints "Ninja" correctly, but does not use it and also why it works after I type export CMAKE_GENERATOR=Ninja in my terminal. By my understanding, the export command sets an environment variable for the current terminal session and adding an environment variable to the .bashrc sets it for all future terminal sessions.

What I have tried:

• I used printenv, which does not show the environment variables I set in the .bashrc, BUT, if I type export CC=/usr/bin/clang for example and then run printenv it does show up in the printed variables. I suspect this weird behavior to be an indication of what's wrong, but I do not know why this behavior happens.
• When researching this, I have seen posts mentioning that there is a certain order in which the .bash_rc and .profile are being run, but since I have tried putting the variables in all of these files and it not working, this seems not to be the issue. I do not have a .bashrc_profile file, which has been mentioned in posts I have read and by my understanding I do not need one either.
• Ticking the "Run command as a login shell" box under Preferences -> Command of my terminal. This did not work. I have since unticked this option.
• I thought about editing either the /etc/profile or /etc/bash.bashrc file, but since those are read only and I am fairly new to linux, I would prefer not to meddle with such files.
• I have tried to find a fix by reading posts on the internet, but I feel like I have not been able to correctly phrase my question or been able to find a solution.

My .bashrc

# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples
If not running interactively, don't do anything
case $- in
    i) ;;
      *) return;;
esac
don't put duplicate lines or lines starting with space in the history.
See bash(1) for more options
HISTCONTROL=ignoreboth
append to the history file, don't overwrite it
shopt -s histappend
for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
HISTSIZE=1000
HISTFILESIZE=2000
check the window size after each command and, if necessary,
update the values of LINES and COLUMNS.
shopt -s checkwinsize
If set, the pattern "**" used in a pathname expansion context will
match all files and zero or more directories and subdirectories.
#shopt -s globstar
make less more friendly for non-text input files, see lesspipe(1)
[ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"
set variable identifying the chroot you work in (used in the prompt below)
if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
    debian_chroot=$(cat /etc/debian_chroot)
fi
set a fancy prompt (non-color, unless we know we "want" color)
case "$TERM" in
    xterm-color|*-256color) color_prompt=yes;;
esac
uncomment for a colored prompt, if the terminal has the capability; turned
off by default to not distract the user: the focus in a terminal window
should be on the output of commands, not on the prompt
#force_color_prompt=yes
if [ -n "$force_color_prompt" ]; then
    if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
    # We have color support; assume it's compliant with Ecma-48
    # (ISO/IEC-6429). (Lack of such support is extremely rare, and such
    # a case would tend to support setf rather than setaf.)
    color_prompt=yes
    else
    color_prompt=
    fi
fi
if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}[\033[01;32m]\u@\h[\033[00m]:[\033[01;34m]\w[\033[00m]$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w$ '
fi
unset color_prompt force_color_prompt
If this is an xterm set the title to user@host:dir
case "$TERM" in
xterm|rxvt)
    PS1="[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a]$PS1"
    ;;
*)
    ;;
esac
enable color support of ls and also add handy aliases
if [ -x /usr/bin/dircolors ]; then
    test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
    alias ls='ls --color=auto'
    #alias dir='dir --color=auto'
    #alias vdir='vdir --color=auto'
alias grep='grep --color=auto'
alias fgrep='fgrep --color=auto'
alias egrep='egrep --color=auto'

fi
colored GCC warnings and errors
#export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'
some more ls aliases
alias ll='ls -alF'
alias la='ls -A'
alias l='ls -CF'
Add an "alert" alias for long running commands.  Use like so:
sleep 10; alert
alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '''s/^\s[0-9]+\s//;s/[;&|]\s*alert$//''')"'
Alias definitions.
You may want to put all your additions into a separate file like
~/.bash_aliases, instead of adding them here directly.
See /usr/share/doc/bash-doc/examples in the bash-doc package.
if [ -f ~/.bash_aliases ]; then
    . ~/.bash_aliases
fi
enable programmable completion features (you don't need to enable
this, if it's already enabled in /etc/bash.bashrc and /etc/profile
sources /etc/bash.bashrc).
if ! shopt -oq posix; then
  if [ -f /usr/share/bash-completion/bash_completion ]; then
    . /usr/share/bash-completion/bash_completion
  elif [ -f /etc/bash_completion ]; then
    . /etc/bash_completion
  fi
fi
CC=/usr/bin/clang
CXX=/usr/bin/clang++
CMAKE_GENERATOR=Ninja

My .profile

# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.
the default umask is set in /etc/profile; for setting the umask
for ssh logins, install and configure the libpam-umask package.
#umask 022
if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
        . "$HOME/.bashrc"
    fi
fi
set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi
set PATH so it includes user's private bin if it exists
if [ -d "$HOME/.local/bin" ] ; then
    PATH="$HOME/.local/bin:$PATH"
fi