Timeline Artwork moving position randomly

Hi all! I am working through some client animations - the whole thing looked great, I saved it down/exported (no issues). I realizee there was a small mistake in the artwork (my fault) so I opened the file back up to find pieces of artwork on my timeline (multiple layers, noticably pieces of artwork that were not in a group) have totally shifted position and I am left with a mess of a file to cleanup/adjust!

Any info on this bug and how to avoid it? I am worried it was because of clicking 'match contents' or something like that. It happened earlier and I first thought it was an issue with opening the file and saving in an older version of Animate, but this last example makes me not so certain.

Thanks! -Sarah