I have several CMake projects located inside a folder on a secondary hard drive, which is symlinked in my home folder. If a file is opened by GDB (e.g. when stepping into a function that is defined in an unopened file), Qt creator will report that the file is not part of any open project, and the file will be parsed improperly. Opening the file from the Projects pane first does not produce the same issue.

I mostly use Qt Creator 4.11.0 as it's what's provided in the Ubuntu 20.04 sources, but the issue is present in 4.13 as well.