Mastery for both hantu port and Siberia map have stopped, I’m currently on 16/20 hantu, 13/20 Siberia and the mastery xp bar has disappeared from the post game results, and no unlocks are working on with sniper rifles (no extended mag at all) still got 5 rounds per rifle.
Playing on Xbox series X, deluxe edition, have done a carry over from hitman 2 before I started playing hitman 3 at all (had to wait 48 hours after launch before playing because of the stupid carryover system)
I haven’t seen such issue being reported here. In order to ensure the dev team sees this, you may want to post it on this thread. Hope your issue gets fixed eventually:
With the connectivity issues persisting, I had thought I’d play a round or two of Sniper Assassin, but I just noticed that the mode is online only, even though the coop function has been removed. 
I was also on 16/20 in Hantu and 13 or 14/20 on Siberia… There is no mastery xp bar anymore, so I cannot progress the level further, because there is no mastery level (and no weapon upgrades by the way). My 27/27 unlocks are there though… So as of now I won´t ever be able to unlock the Druzhina 34 ICA Arctic for Hitman 3.
I really hope devs fix this 
And all my mission storys for Hitman 1 and 2 are at zero by the way, don´t know if that is intended to not carry over. (playing on Epic by the way)