Set Matte Effects Missing

[mobilefidelity]

Hello all. I'm still using Adobe 5.5

I've just been given an AE template to work with. Upon opening the .aep work file I get a window saying: 'This project contains 1 reference to a missing effect. Please install the following effect to restore this reference ("Set Matte").

When I checked my effects panel, I noticed that I have the effect "Set Matte" (16bits), below it is another tab Missing effect "Set Matte" (8bits). If I have (16) I can just use it and match what the missing "Set Matte" (8) was set to. However, when the layers, I see no trace of "Set Matte" being applied. 

I would appreciate a response. Thanks!

[Mylenium]

Set Matte was updated at some point indeed. What you experience would happen if you downconvert a project from a newer version to an older one. The rest we can't answer, but it seems to me you haven't actually dug into the tons of pre-comps. Clearly, if the warning pops up it is being used somewhere and the outcome just looks wrong, further enforcing this assumption. Double- and triple-check again.

Mylenium