Summoning Leader on buffed Tokens

Foznertep

I was wondering if this was working as intended or not. Let's say I have a number of Angel Tokens on the board and I cast a buff on them, e.g. Sentinel's Mark, and then later summon Resplendent Angel. Once they have converged, both Vigilance and Life Link are gone. Is this a bug? Because it surely seems odd. 

EvilDead

The Leader turns them into a different creature so.....yeah

Foznertep

I feared as much