I tried unlocking the third camo challenger for the X52 Resonator (BO6 gun) in Warzone (post BO7 integration) and the camo challenge: Get 15 eliminations; will not show any progression even though I've gotten 15 eliminations.

Do the camo challenges in Warzone (post BO7 integration) for BO6/MW3/MW2 guns no longer work?

If not, how are people supposed to complete the camo challenges if they haven't purchased BO6/MW3/MW2?