I have this problem too.
I had a favor item and several matches worth of favor saved.
After one of the patches, that got reduced to 160 favor (!?!) and is now stuck at that number. I'm also unable to use that item in any match - it's like I didn't get it at all. Can't earn favor even though all I play is multiplayer and we win most matches. :/
All of my friends have similar problems, though some are more lucky and got stuck at higher favor levels or with items unlocked.
We're forced to host our own games and play with favor off - which is kind of fine because favor items are incredibly imbalanced and reduce the gameplay depth when enabled.