My camera gives me MTS files, which I then almost always encode to an uncompressed avi at 1920x1080 1:1 pixel aspect ratio for editing purposes. However, suddenly and inexplicably, Premiere Pro and the Media Encoder have both decided that the upper limit is now 1620x1080. My original footage is 1920x1080, so this makes no sense. I've tried making sure the software is completely up to date, and this does not fix the problem.
Does anyone have any possible insight as to what might be going on and how it might be fixed?
Never mind. Problem solved. I would figure it out just immediately after posting the question.
Lemme guess... you didn't uncheck the Link Aspect Ratio button?
By the way, you probably don't want to use the Uncompressed MS AVI option; if you want an uncompressed file that will be a bit more compatible, select Microsoft AVI with the codec set to "None." Other options for losslessly compressed (and therefore smaller) AVIs would be the Lagarith Lossless Video Codec or the Ut Video Codec Suite.