[Fenris447]

Oooooh I figured out the issue. So the way the Tasha’s spells are presented, they’re part of the Class Feature Variants. That means you need to enable those features on your Hero before you use them. From the Configure Hero menu, find the Optional features section and check the box for “ Always show Tasha's Variants”. This will enable a tab for Tasha’s Variants. Select the Class Feature Variants option, then select the expanded sorcerer spell list. That will enable you to see Mind Sliver and any of the other new spells the sorcerer receives.

EDIT: I’m going to look into this a bit more. I’m wondering if we shouldn’t treat those spells the way you expected, the way we treated the XGTE spells, where you select the source and they’re automatically available in your spell list. I’m not at home right now so I can’t look at my copy of Tasha’s.