Also mp2 files have black bars on the sides now when making video for DVDs yea we still need those.
This has always been true for downrezzed mpeg2 files. Set the crop to "scale to fill" on export.
Well it use to save it with your presets but now it doesn't, it was kind of out of sight out of mind but it now defaults to black bar and you can't save it as a default you have to now manually set it every-time as the last thing you do before exporting. Sorry but this is not an improvement and not as you said the way it ALWAYS been....
Sorry, I only meant that it "always" required the crop. That said, I just tested (after waiting for the Win update to 1803!) PR 12.1.1, and a) the scale to fill stayed put for the next export and b) I saved a preset and, after changing away from the format, came back to MPEG2-DVD, a regular preset show black bars, and my saved preset had scale to fill. Don't know what to say! I'm always willing to confirm a problem; just can't this one.
Are you able to use the H.264 format, preset Vimeo 480p SD Wide? (I was.) Is your preset from an earlier version, or made new?