Thanks Ann for your comment I do see the 12.1.1 update and I will give it a try.
I am pretty certain my graphics are not the issue and that the problem is a bug in PP 2018.
Thanks for your reply. I’m looking for others to verify the issue and try a PNG import to see if we have identified a bug. I have cut the project in PP 2018 and if i recall timelines in PP are not backwards compatible.