I have been experiencing something similar, where I an paste images into a table, on the latest beta client for Windows, and after syncing, images are removed. Worse, I can sync, and everything looks OK, so I navigate to a note in another Notebook, and when I go back to look at the previous note, I see almost all of my changes GONE! Images pasted into tables, all GONE! Cannot rely on this anymore. Very disappointing. Having to re-paste, hoping that it sticks for real. I have no choice but to use the non-beta client, now, until the issues with the beta client are 100% resolved.