Ah yes:
If you have 10 Monolith Sigils, Valhawks won’t appear in your battles until you have less than 10 Monolith Sigils
I see it’s not in the patch notes so I’m adding it in now, I’ll also make sure the help center article has that info as well
No ETA sorry but I checked to make sure we have a bug report for it and bumped it.