Does anyone here use Xmarks? I need help (details inside).

Xmarks had been recommended to me as way to keep browser favorites (aka, bookmarks) in sync among various devices.

But I seemed to have discovered a downside. I cannot delete any bookmarks that I no longer want! Also, I cannot put the bookmarks in a different order. When I delete a bookmark, it simply gets placed at the bottom of the list, it does not go away.

Is Xmarks responsible for this behavior? If so, how can I fix this? Their Help files have been no help. If not, what is the cause of this, and what can I try?

My PC is running Win 7 and IE 11.

Thanks!