Edge Dev Favorites - reappear after delete + cannot custom order

Hi,
I've been having the same problem, have seen lots of other posts about it as well.

the only solution right now is to disconnect your other devices connected to the same Microsoft account and syncing to that same account.
so like if you have 2 Edge insider browsers on 2 different devices (computers, tablets etc) or even 2 browsers on the same computer, sign out from one of them. this also applies to phones and computers, preferably sign out from your phone.

this is very important and existential issue with sync servers, they are not reliable enough, the browser is still in experimental channels and we will see how they will sort these problems out before January 15th which is the release date.

there is also another problem that I don't see in your post.
if you try to set a favorite to icon only, it will revert back to the original form soon. this problem can't even be solved by turning off sync on other devices, i think only solution is to turn off sync completely everywhere.

try to use another stable browser such as Google chrome stable to keep your bookmarks/favorites safe there and only import them to Edge insider once everything works as they should.