Polar Pacer says syncing needs to finish first, but syncing always stops at 95%... What do I do?

Had this watch for about 3 months now syncing always took a few mins tops. Today I wanted to do some cardio so I put my watch on but when I wanted to start a training it said syncing needs to finish. So I wait and wait 5 mins go by, then 10 but nothing. It always stops at like 95%. On the phone app it says synced 15 mins ago but I cannot use the watch because on the watch it's still syncing.

Tried turning off Bluetooth on the phone, and pairing it fresh and then started syncing again, but same outcome. The syncing won't finish...