I copied avid media from it's original location to a portable drive along with a copy of the project on that same drive in order to send it off to another editor.
I opened the project on the transfer drive, and unplugged all other drives so I could open under the same conditions as the intended recipient and see if everything had worked. I noticed that on one of the shoot days, if I scrubbed through a timeline made of the rushes for that day, the video playback exhibited bizarre problems. It almost looked like bad reception on an analogue TV, stray lines all over the place and something like the equivelant of a dicky vertical hold with bits of the image way too far up in the frame from where they're supposed to be.
I immediately assumed the issue was a corrupted file transfer or possibly even corrupt files from the source. I confirmed it was fine at the original source location where it was copied from so that left the copy on the transfer drive. I deleted that copy, and re-copied it. Same problem. I deleted it off the drive again and then re-imported it from the original rushes. Same problem. I copied the rushes to a different drive from the source and different to the transfer drive and had the project opened from the transfer drive, read from this 3rd drive. Same problem. I tested the master clips, not just the sequence, same problem.
Then I tried dragging the .mdb file from within the MXF folder on disk where the clips were contained, in to a new bin, and suddenly the clips were fine. That was weird, but glad it was fixed, or so I thought. I made a sequence of those clips, still fine. Then I remembered that I'd have to sync these master clips to the corresponding dual system audio. Bang, exact same issue all over again. I checked the original malfunctioning sequence, it was using sync clips that had been made prior.
I had been attempting to sync the dual system sound by timecode, just as a random stab in the dark, I tried a manual sync, still the same issue occurred. Then I tried pushing it way out of sync, still the same issue occurred. Then I put random audio that had nothing to do with the clips and was not supposed to sync with it, and it worked fine, no issue at all. So strange. I tried re-importing the audio and re-syncing and once AGAIN the same issue occurred.