Okey...
Plex doesn't play local files, it always plays streams from the Plex Server.
Which means SVP doesn't know which local file is actually playing.
Basic profile conditions (width, height, etc) always works, while "file name / path / extension" and some others won't.
This's what I meant by "it should work as long as you see some text in the condition value when you add it while the video is playing."
When you add new "file name" condition and you see the empty value field - this means SVP has no information about the actual file name, and this condition won't work.