I play killer anaad have aall the invitatiosn every single match, i played around 15 matches so faar and not aa single maaaask has been earned
To unlock the masks you need to have enough charges from your invitation left. If you keep using the effects but don't pick up an other invitation you won't unlock anything.
As Annso_x mentioned above, the invitations need at least one full charge when the gates are open (and as Survivor, you're alive), one survivor is left and the hatch spawns, or the game ends. Are these being met, but still no masks? Also, double check the Event Collection page to check if you can <3