Lost an AirPod and find my isn’t working

So, some how I lost the right AirPod. Click find my and says mismatch and not set up yet. So, find my is useless being I can’t do anything like notify if I come in range of it. Oddly enough, when I go into settings on my phone, it shows an updating battery level for both. So I am limited in time for finding it due to the battery level, and I can’t set up play sound or notify due to find my not working, yet my phone is seeing the battery level and it is showing it go down as time goes by. Anyone have any idea how it could be checking the battery yet not able to find in the find app. This is very disappointing that the sole purpose of the app is to locate lost things and yet it can’t be used cause one is lost