Audio drifts out of sync in FCP Viewer
My video file was an .mkv and I converted it to .mp4; however, I believe the converter I used converted it to H.284 because the video will not open in Final Cut Pro 7. I used Compressor to convert it a second time to Apple ProRes HQ, and the file plays perfectly fine in Quicktime. But once it gets into FCP, the audio begins to drift out of sync.
Other articles I have read all say to check the sequence settings, but the sequence settings match, and also the issue is apparent in the Viewer as well, not just on the Timeline. Are there any better solutions to try? (Including the possibility of converting the .mkv properly the first time.)
MacBook Pro, iOS 8.1, OS X Yosemite