iOS Messages phone storage usage different from iCloud I have a conversation log in my iPhone (iPhone 11 Pro, iOS 14.0.1) that goes back to 2009. iOS says it is occupying 15.96GB:

I have the phone set to save everything in my conversations (e.g.: high resolution images and videos) and I don't want to change this setting.
I want to back it up in iCloud so I upgraded to 200GB and connected my phone to WiFi and a charger. It started displaying the “Uploading messages” message and progress bar at the bottom of the screen. This message and progress bar no longer shows up and it has only uploaded 8.1GB:

This number doesn't change anymore regardless of me charging the phone or not. I don't have Messages iCloud sync activated in any other device. Any idea why this seems to have gotten stuck?
The number eventually grew to 15GB after a few weeks. Still no progress bar visible but at least it arrived there so I guess it just takes a long while, even with WiFi.