I posted the very same problem in the Technical Support thread HITMAN 3 - Technical Support - #1127 by Ligox
No access to Envy despite it being owned and installed per my Epic Games Library.
I’m buying each individually (not the pack) and all have worked so far. This is the first time it doesn’t with Envy and now others are facing the same issue.
I tried all the verifications of game files, selecting and unselecting this DLC specifically, restarting PC. Everything but downloading the entire game again.