Merged Clip Markers Have Disappeared

Hello. 

I'm working in PP V:25.4.1 (Build 3), in a Production, with a Project that has my sequences, and a separate Project with the raw footage. 

I was having trouble putting clip markers on a merged clip in my sequence, so I went up to the Source window and did it from there, with comments, and that seemed to work. BUT the next time I opened the project, most all of my markers were gone (I only had 7 left, out of about 50). I looked everywhere to "re-jigger" the markers but they don't seem to be anywhere.

I have other merged clips in different sequences in the same project, where the markers work just fine, but this weirdness has happened in a couple of my other sequences now that I'm looking back. 

Anyone know why this might be happening, and maybe my markers are still living somewhere!? 

Thanks!