Smartwatch won't connect via bluetooth anymore

Smartwatch won't connect via bluetooth anymore

My mom tries to #bluetooth pair her smart watch and her phone. But every time she enters the correct validation code in her phone, the watch denies the #pairing.

her watch is a Suunto Peak 9 Pro
Smart phone is some Shift Phone 5 on Android edit8/edit
watch and phone have been factory reset
app has been reinstalled
watch to the latest firmware
phone bt cache and data have been deleted
phone network data has been reset
the watch can connect to another phone
her phone can connect to other bt devices

Any suggestions? What are we missing?
@android #boost #boostplease #teilen #followerpower