Hey guys. It has been fixed after updating my Note 8 android system to Oreo today. It's working fine with all added fingers. but I haven't added any new finger after update!
I am also experiencing exactly the same issue after removing one of my fingerprints on my Note 8! I have removed and added fingers again, restarted phone, disabled and enabled 'unlock with fingerprint' option, but nothing happend, it still says "fingerprint not available at the moment"!