This almost has to be a mismatch of settings somewhere in the process. Can you post screen grabs of Sequence Settings used for the edit, as well as a shot of the Media Encoder export settings? And what format/size was the source video from the camera?
For instance, if the source video was 720p, but you accidentally edited in an SD sequence (720x480), but then exported as 720p, and bringing that back into the SD sequence. Something like that is happening.
Safe Harbor Computers
Use the video to create the sequence by dropping the video on the New Item button instead of creating the sequence from scratch.
Usually when I finish edit a video, I don't have need to bring it back into Premiere
You shouldn't be bringing a finished video into Premiere Pro even when you do need to make changes. You go back to the original project using the original media.
I agree about not bringing a finished video back into Premiere for editing, but I thought I was finished with it and it was not an important project, just an experiment. So when I thought I was finished with it, I deleted the original media to save disk space. And while, as I said, I agree with you on this, that doesn't explain the stated problem.
I also agree that it is probably some mismatch between Sequence Settings and the Export settings. I think this may be because I'm still fairly new to Premiere, and I don't fully understand Sequence Settings. One window that opens when I first start Premiere is called the New Sequence window. This appears to be where I'd set up Premiere from the specs of my clips (almost always .mov HD files at 1290x720 29.97fps NTSC), but none of the choices in that window equal my footage. Most of them are for DV footage (which indeed has smaller size then my 720p clips). I suppose I could make a custom setting but I'm not sure just how.
When there is an install issue with Premiere, or it is not fully activated, it will sometimes show a very short list of Sequence options, mainly DV choices only. Do you see AVCHD, DSLR, HDV, listed?? If not, it is broke.
As suggested earlier in the threads, there is a New Item button at lower right of bin where the clips are, drag and drop a clip onto that icon and it creates a sequence to match your clip. Unless Premiere is having the install issue. For your clips, you could use "AVCHD > 720p30" and that should work.
Safe Harbor Computers
I figured it out!! I went into the New Sequence window and clicked on the Settings tab and created this Custom sequence setting................
A little hard to read at this image size I guess, but this seems to load all my 720p clips and projects at the proper size (and they play fine). Does anyone see any problems with anything in this setting?
That looks good, however you're Premiere install is not good, need to reinstall so that you get ALL the presets, the entire window should be full of options. Of course, verify you are fully activated first, but if that doesn't work, reinstall (deactivate first under HELP).
Also concerned that the original edit may have been at DV resolution, so even though you exported to 720p, the video may have been dropped to SD first then back to HD so if that happened you lost a lot of quality, but nothing to be done if you don't have the source material/project any longer.