[HELP] QTGMC appears to not be deinterlacing footage (or not doing so correctly)

[Selur]

2) Load one of the interlaced files, I've been working with. RESULT: Filtering has now been changed to "TIVTC (Vapoursynth)"

That should only happen if your source is detected as 'telecine' or 'telecine (soft)'. => check what the source is detected as.
I did change some code not to long ago that changes the detection a bit.
Can you share a debug output (better a sample) of one of your sources where this happens?

Cu Selur