Raynor, Kerrigan, and Artanis are capped on level 5, but they were all on level 15 on the EU server. My EU account has Mastery = 85.
This is the same for me. Raynor, Kerrigan, and Artanis stuck at level 5.
They were level 15. NA (Central United States).
Seems this has happened each year looking back at the some logs with similar cases.
It looks my mastery and prestige points are back and available again on Kerrigan. TY Blizzard for doing something about this problem.