When targeting actors, make sure to wrap the actor id(s) in brackets like so:
[1,2,3]
or
[1]
Or simply put 0 (without the brackets) to target all actors. Did you double check the template item and made sure it has stats?
Viewing post in Collection Effect Plugin - RPG Maker MZ comments
Ohhh okay, I was missing the brackets! Thank you for that. As far as the template item, yes it has stats both in my 'official' game and in the blank test project. :) I can get it to work fine in the blank project, up until I added the VisuStella Core plugin? After that the stat boosts stop being applied.