The problem is most likely the file size. I have some 800 bookmarks but no favicons, so the file size for the .html file is less than 200 kb. There is a way to remove favicons from a bookmarks.html file. See this page and look at step 2.
Hey thank you both very much! That makes sense that it would relate to Sync. I have Opera browser on 2 macs, and on my android phone. (It's been my primary mobile browser for 12 years! ) ... I guess I should do a Bookmarks Export to an html file, and at least protect the state of "how things are right now"... Now that it's clear to me y'all don't/didn't have this problem of shifting tile order, I will focus on my end. Good night
If he completely reinstalled his OS - to the point of needing to recreate the user account - then the actual password used wouldn't matter. If you have to recreate the account then your locally-stored passwords would be unreadable. Not that it should matter to Sync.
I do agree that the mgmt is not that intuitive, especially if you are using List mode. But what you can do is to Click & drag, as if it was your Desktop. I've attached a print screen, hope it helps to understand. What I usually do to ease the process, is to change the view mode, to the option in the middle, on the top left corner.