An error occurred while saving the commentMarc De Coster commented
I had the same problem today. But I discovered the reason why all my markers disappeared from my sequence: I put it in the source viewer and click the "open sequence in timeline" property in the tools. Since then, bam, no m ore markers.
But I could get them back. I opened an older autosave version and copy-paste the same timeline with the markers in the current project.
It's still a big issue though. Adobe should work on it quickly