I am having a similar issue, but it is not consistent…but often. Also some stills disappear from view, but are not red in the timeline when this happens.
I don’t have this issue with After Effects, so is there a way to use programs effectively? I do know how to use premiere pro but to import into premiere pro from after effects I would have to buy the premium or the master collection to have the dynamic link. Vegas after just 1 day of playing with is seems to be a little easier to work with.