I just encountered the problem of not being able to synchronize as well, in my case I got an error message of ‘unknown error’, and found a makeshift solution:
- install iTunes
- in iTunes: select the device and back it up - the data created by this is machine readable only, some kind of encryption apple uses
- install iMazing - a program that allows to browse iOS backup files and shows the backups folder structure
- open iMazing - in my case it found the backup file automatically. Locally stored backups even are sorted by device.
- select the device, which’s backup you want to access and navigate to ‘Data’ on the left side tab
- select Apps
- search for QField in the list off apps and navigate the folder structure to ‘Library/Application Support/OPENGIS.ch/QField/cloud_projects/ [QField account name]’
- from here you’ll have to search through the folders for your project
- select folder and click on ‘copy to PC’, select the directory on your PC you want to save it to
- celebrate! you got your data back
With the iMazing trial version you got 10 folders you can copy to your PC. In my case two were enough to find the data, though for future projects I wish to see the QField Cloud sync problem with iOS fixed.
Be welcome to share this solution with others! Just please always refer to the original post 
Imported from GitHub comment by @bloqbreaker on 2024-06-11T18:48:21Z