Bug Report #1967624284

Good Day,

The Witch's Demon Form does not seem to allow Spirit Gems (Grim Feast - 50 spirit) to be active unless it's equipped in the secondary weapon slot. However, once Demon Form is deactivated, it cannot be reactivated again if there's a Spirit Gem active in the Secondary Weapon slot even if the character has enough permanent spirit (60 for unfinished campaign Act 3+).

Update: It was the Vitality persistent gem that made it unable to be equipped.