Issue with Apple Watch storage constantly filling up.

Hello,

I'm having an issue with my wife's Apple Watch Series 1 and was hoping someone here may be able to help me as my 2 attempts at Apple support helping me and my own troubleshooting has not solved anything thus far. What happens is that the watch's internal storage get's completely full with who knows what. I've checked to see what is using up the space, but when I add everything up that's taking up space together I get less than 200MB used, and because the watch's storage is full it then starts not working properly (like not being able to erase messages, silence alarms, and constantly getting a warning that says the storage is full...etc). I've tried so many things to try and remedy this...including,

• Factory resetting the Apple Watch and then setting it up as a new device on her iPhone XS.
• Checking that her phone is not syncing over any photos, music, and other, and also making sure it only has the default Apple Watch apps installed on it.
• Resetting her iPhone, Resetting the watch, and then setting up both the iPhone and Apple Watch as new devices.
• Getting a brand new iPhone 12 Pro (don't worry she wanted to get one anyways, lol) and setting that up and then setting up the Apple Watch as a new device while also doing point 2 above.
• Checking her iCloud storage and wiping anything that we think would maybe upload to the watch (iMessage, reminders, etc).
• Signing out of iCloud on all her Apple devices, and then signing back into iCloud on all her devices.
• Restarting the Phone and Watch multiple times.
• Bring it into the Apple Store and have them run a diagnostics on it only for everything to be "fine".

I've even tried to sync her Apple Watch to my iPhone and magically this DID fix the issue. Attached to my iPhone it no longer syncs a bunch of random stuff and no longer gets full. So that rules it out being an issue with the Watch's hardware.

I've also tried syncing my Apple Watch on her iPhone and it WILL do the same completely filling up of the storage capacity. Lastly I've wiped her old iPhone XS (as she now has a brand new iPhone 12 Pro) and set that up as a new device, logged into it with MY apple id, synced the Apple Watch and it worked fine. No syncing weirdness filling up the watch.

This makes me think that the issue maybe has to do with her iCloud account. But like I've already stated...I've cleared most of it out except Phone backups, photos (which I don't sync to the watch), and her safari bookmarks and such. I'm not sure what else to try or what to do, was hoping someone here maybe could help me out. Maybe I missed trying something? Maybe you've had a similar issue and were able to resolve it. Please help, would really appreciate getting this darn watch working again.

Thanks. 🙂