QtCreator sometimes locks up busy looping if file is modified externally

Occasionally, QtCreator 6.0.0 beta 1 locks up busy looping on one core indefinitely, UI unresponsive. This often happens after you modify the current source file in an external process, then switch to QtCreator and try to navigate the file. QtCreator shows a dialog offering to reload the file. It may hang busy looping in this dialog or shortly after you choose to reload the file. This doesn't happen 100% of time and may be correlated with how much modifications are made in the external process (in my case it happened when I inserted a large comment in the file, at a place before the current cursor position in QtCreator).

While busy looping, I attached strace to the qtcreator process and it didn't produce any output (i.e. no system calls were made). I attached gdb to the process and captured a few backtraces (attached). It looks like the process is busy looping somewhere in code highlighting.

This never happened on QtCreator 5.x on the same code.