Thank you for reporting this issue, @ukheather. When you say the iPad and iPhone stop syncing, do you mean they no longer send their data to the desktop device, or the desktop no longer sends its data to the iOS devices?
When the iOS sync page crashes, and it appears as though the devices have been removed from the sync chain, do you eventually see these devices removed from the brave://sync/ page on the desktop device too?
When these devices (iPad and iPhone) are re-added to a sync chain, are they being added to the existing sync chain upon which the desktop currently resides, or are you creating a new sync chain each time (and adding all devices to that)?
Thank you again for your patience, and helping us to gain a better understanding of this issue. I look forward to doing whatever I can to improve your experience with Brave as promptly as possible.