I had the same issue. I contacted Apple Support and they said that this is the way bookmark syncing was supposed to work and that all you could expect was for the bookmark to show up "somewhere" on your other devices. I didn't buy that since it had always worked before. After trying many other things, here is what I did to fix this. On my iPhone and iPad, I turned off Safari in iCloud deleting all bookmarks on both devices instead of saving them. On my iMac, I exported my bookmarks under the Safari "File" menu. I then deleted all bookmarks from Safari on my iMac. I signed into my iCloud account from my Safari web browser. I went to my name in the upper left hand corner and went to "Account Settings". Scroll to the bottom and you will see "Advanced". I selected "Restore Bookmarks" and deleted all bookmarks there. I closed out of everything, rebooted everything, imported the bookmarks I had exported and put them back in my Favorites file in Safari on my iMac. Turned on Safari in iCloud on my iMac and then on iPhone and iPad. The bookmarks showed on all devices in the proper order. To test it, I added a new bookmark to a folder. It appeared at the end of the list in that folder on all devices. I then moved that bookmark to a new folder in the middle of the list in that new folder. It appeared in that location on all devices, eventually. I found if I made the move on the iPad, the change appeared almost immediately on the iPhone, but would be a couple of hours before it appeared on the iMac. Anyway, my bookmarks are pretty fleshed out with what I want so I don't add many anymore and haven't tried it again, but I hope it continues to work. BTW, I have 317 bookmarks in Favorites in 7 main folders, most of which have a few subfolders.
