The synchronization of audio with the TC changes when WAVE files with TC are cut into sequence.
If I mark an in point at 01:00 and out at O2:00, the resulting aux clip in the sequence looks fine from a TC point of view. In is 01:00 and out is 02:00, even when reopened in the viewer. But the actual audio in the new sequence clip, is the audio from roughly 1 second earlier relative to the original clip. The viewed waveform reflects what you actually hear.
Clips were imported with import broadcast wave set to “non-drop” and the sequence is non-drop. The sequence is 720p59.94 (not 29.97)
I don’t know how the original WAVEs were created accept that they have a TC track reported in QT, though QT can’t seem to read it.
Hillmann & Carr Inc.
What’s the sampling rate of those files?
The problem you describe sounds a “NTSC Slow Second” problem where it needs 1.001 second to play 1 second of real world AV.
Try to start over the project. First close any open project. Then choose a new “Easy Setup” for the settings you need. It’s a good idea to quit FCP then and re-launch. Hopefully FCP has forgotten you BWAVs then. Now import the files again.
Regarding the timecode, the audio timecode from BWAV files is a “TC64” which differ from “TC32” of normal video files. In QT Player you can make it visible if you check the box on the left of the track – DO NOT save that. It’s displayed in “samples after midnight”.
You may also try my BWF2XML which creates a QT wrapper for those BWAVs which use the standard QT timecode. This will fix the files playback speed. Though in FCP you might see a bar for the audio this means that FCP no longer sees them as native 48 kHz. They still perform real time.
BWF2XML can be found at: https://www.spherico.com/filmtools/BWF2XML/index.html
Quite a lot of US movies where done with the help of it.