CLion C++ New User having trouble getting basic syntax checking to work.

We have code base that has been maintained in qt-creator and eclipse for years.  I recently sat down to evaluate CLion as a possible replacement for those tools.  I was initially very happy with the tool but then I started to notice that basic error checking seems to not be working.

Importing our existing CMakeLists.txt was seamless, we saw no errors.  Loading our code immediately presented a bunch of warnings from Clang-Tidy that all seem like legitimate issues. 

At one point in cleaning up some of the Clang-Tidy issues I renamed a variable and noticed the code didn't flag all the references to this variable as unknown. 

Poking around I started to add random lines into my function akin to. 

Fish Fish Fish: 9;

To my surprise there were no errors what so ever flagged on the obviously incorrect line.  I'd have hoped that CLion would have told me that Fish was an unknown symbol, and complained about the strange :

Is there some setting I have wrong or something I'm missing to get basic C++ validation working?

I'm working in a Fedora 34 environment if that matters.