Mysterious lack of video support on desktop QGC Daily Build

I’ve been working on getting a video transmission system off the ground for some time now. I had been running some stand-in testing on a Samsung tablet, having QGC built with GStreamer through QT. While waiting on some hardware solutions to arrive/be developed, I wanted to port my currently fully functional RTSP pipeline into QGC to at least be able to begin integrating the system with our AP’s and doing some more wholistic testing. However, despite having all possible GStreamer plugins installed on my host computer, whenever I launch QGC from QT, I am unable to select any options in the video drop-down menu - the only visible option is “No Video Available”. This is puzzling - the android build functions well for video streaming, and the host PC is perfectly capable of running GStreamer for all of my other testing. In the General Messages’ output when building and running, QT even says

Project MESSAGE: Including support for video streaming 

The only error or non-conforming message thrown throughout compilation, building, and running, is a single line:

[Inexact] Cannot read /home/<user>/qgroundcontrol/user_config.pri: No such file or directory

I am very new to QT, and basically have only used it to compile QGC. I have no idea if this message relates to my issue at all, nor have I any idea where to start debugging this problem. I have changed nothing from source, and followed the instructions to build with video support to the letter. If anyone has experienced this issue and knows a fix, please point me in the right direction. It might be worth noting that this Daily build is from around a month ago, my next step is pulling a new daily build, but given that the Android version correctly compiles with GStreamer, the version doesn’t seem to be the problem here. I am building on Ubuntu 20.04, using QT 5.12.6 and GStreamer 1.16.2. Any help is greatly appreciated.