I am extracting multiple types of items from 1 location, and I would like to send specific items to specific destinations (multiple). I am able to use the filter destination tool to specify locations, but no matter what combination of whitelist/blacklist/inverted I use, items either go to the first available inventory, or don't get extracted at all. Is this a bug? If it is user error, can you help me understand how to achieve this?

You are using the sorting mode Nearest First you have to use Round Robin for that.

Hmm, that would imply that "Nearest First" ignores the whitelist, but "Round Robin" respects the whitelist. If that is true, it's definitely not obvious.

No, but whitelists just apply for the destination that is set.

I had this issue at first. Had a chest with extraction and upgraded it to a basic. Then up to advanced. Filtering didn't work. I broke the chest and pipe and replaced, filtering worked.