Mattes randomly change

I've notived this issue since I first moved from Avid DS to Premiere years ago.

Mattes seem to randomly change for no reason. I understand premultiplication and matting.

Last night was the latest, simple example. I built a graphic in AE and imported it to Premire and it worked perfectly (Pic 1). Output the file to client for review and closed premiere.

When I reopened premiere, the comp looked like Pic 2. I changed NOTHING, simply closed and reopened premiere. No amount of changing the interpretaion of the file got the original look. I had to go back to AE and rerender and replace the files.

This was a minor problem since I was fully responsible for the project, and the timeline was light. But in tight situations, using a team, on a quick turn project, this becomes a problem. This has happened on multiple machines, with many versions of PP since my first PP project. I was learning PP when it first happened and I assumed it was something I did but couldn't find a fix. Yesterday all I did was close PP, then open it a couple hours later and it was messed up.

This change was obvious, but it's not always so apparent. I've spendt a lot of time proofing outputs because to this over the years.

Has anyone else seen this and does Adobe have an explaination?

Thank for any help.