When I have this problem, it’s playing on my computer, going through an AJA IO, and either onto my monitor, or to my Beta deck. Worst part is it’s not a straight “it’s off by X frames” problem, and sometimes it seems as if it’s off more than other times, so I get it lined up PERFECTLY, but then re-edit some other area and the audio is out os sync… again.
And what I see/hear on my computer during editing is pretty much what I get on tape.
Does that help?