fails to exit on Fedora 35

[tabowling]

After installing these make dependencies, this mixer seems to work great! However, it fails to exit/close properly.
dnf install cairo-devel pango-devel mesa-libGLU-devel lv2-devel

After starting from CLI, it outputs a "caught signal" message but never exits and frees the console after click the X icon to terminate the GUI window. But I see no other GUI artifact on the screen or in taskbar.

[tbowling@tbowling scarlett-mixer]$ ./scarlett-mixer 
caught signal - shutting down.

To resolve, I had to open a new terminal, and kill <PID>