Using 1.9.3 of the mod and have noticed that when I have a High Filter Module 3 (haven't tested with other tiers) wooden slabs of varying kinds do not seem to be pulled through to the container even though they are in the allowed list. Other items in the list are being pulled through correctly but none of the wooden slabs I've tested are getting pulled.

If I put a container with no filter they get pushed out to that without a problem.
Stone and cobblestone slabs appear to be working fine when using a filter module.

I've actually just run into the same issue with White Sand too, which comes from the mod Oh The Biomes You'll Go. Don't think it's directly related to the mod though since at least some of the wooden slabs I tested with were vanilla variants.

So I'm not sure why but after a server restart this seems to have resolved itself. I ran into an issue where I couldn't get anything at all to move to a chest with a filter setup for the items to be allowed so I thought I'd try restarting and then that filter started working so I tested the others and they seem to be working now too.