If you are seeing this error...

"Unknown timecode frame rate: 29970/1000
Please use the Help > Report a Bug menu item to let us know about this. We'll default to 30fps, but that's probably wrong."

... here's an explanation and workaround:

InqScribe will detect 29.97 if the app that generated the timecode track marked the frame rate as 2997 / 100.

We're now finding a number of users reporting timecode tracks marked as 29970 / 1000, which is a new way of marking 29.97 that InqScribe doesn't recognize. We're working on fixing that.

The workaround is to not use "Use Media Timecode" in the select media dialog. Instead, select "Start at Custom Time" and enter the start time if it's not 0:00. Then select 29.97 manually within the transcript settings dialog. That should consistently work.