HI,
I had the non-syncing issue over Xmas and have just fixed it to my satisfaction on my setup. I have an iPad Pro 12.9" and a MacBook Pro, and an iPhone pro max.
I had about 70 scriv files in my dropbox folder. On the iPad I could see all of these in the projects view. then I closed scriv on iPad.
I went onto the MacBook, made sure scriv was closed. opened my dropbox folder and in Apps>Scrivener created a new folder where I saved every unfinished project except for about 5 - note of the 5 I kept one is quite big (for me) with hundreds of sheets in it.
So, now I have 2 folders in my Apps>Scrivener folder. I closed dropbox, went back to iPad and opened scriv, It then synced with dropbox. That took 5+ mins, then, on the iPad, I selected all the scriv files that I had earlier backed up into the second folder on dropbox and deleted them from the iPad, then closed the scriv app on iPad.
Then I made a new scrivener file on Mac, made a few test sheets, saved it. On Mac I saw it save fine to dropbox. then closed scriv on MacBook.
Opened scriv on iPad, synced, saw new file, opened it, added new sheet and some text, went back to projects view and saw it sync to dropbox.
Closed iPad scriv. on MacBook opened scriv and opened the file, the edits were in place.
Then I closed MacBook scriv and created a new file on iPad scriv, let it sync to dropbox, Then on MacBook opened scriv and opened the file. No issues.
I have no idea what it is in what I did that helped, but for my use case this works and I’m very happy with it. I hope some of you have similar results. Best regards,