Facebook Messenger crashes when opening messages from just 1 person
So my partner's iPhone has a weird issue, when she opens messenger its fine, when she clicks on anyone, its fine, except for one person (her mum!) when it just crashes back to the home screen.
We've updated the App, iOS is 15.4 (updated in case) we've reset the network settings, logged out of Facebook Messenger and back in, checked there's enough space on the phone (23.1gb) obviously rebooted (update did that) and reset the network settings AFTER the update.
The only other thing would be to reset the entire phone which is a bit sledgehammer/peanut.
The messages work on Google Chrome (Windows OS 10) fine, and we can't figure out the issue. Any ideas anyone???
iPhone XR