At long last, I recently discovered a workaround to the issue I have been having with QLC+ running into a segfault every time I try to use audio input, such as enabling the level monitor in the Audio tab on the Input Output Manager, or enabling an audio trigger widget.
After trying many things related to my audio drivers and audio configuration, I finally determined that changing the configuration on the Audio tab from Stereo to Mono seems to fix the problem. The only issue is, the setting is lost every time I shut QLC+ down, so I have to remember to set it each time I start QLC+.
Not sure what setups this may effect, but the issue is observed on both my laptop and desktop, one with Intel ALC262 audio, the other with AD1883.
It only segfaults in the QT4 version, however, the QT5 version doesn't crash but doesn't get any audio input either, so the feature seems totally broken on QT5.
Q Light Controller+
Official forums of the QLC+ project