Having the exact same problem. But only certain markers suffer this condition. Within the same clip some markers will retain the text and info, and some will just remain there but with all text and info erased.
Additional info: I'm editing multicam (2 cameras), and when I place a marker in one of the cams clips, it gets copied on the second cam clip (which is great), but maybe they are constantly rewriting each other? So the empty info box on the second clip marker immediately overwrites the info I just wrote on the first clip marker. Just a thought. Besides, I'm having trouble deleting some of the markers (some of them just won't erase), so far this is only with clips that erase info but not all of them.