Hello!
It seems like only one of the inserters in a filter loader gets the blacklist signal while the whitelist one is fully functional

Not sure what you mean.

If you set up a filter loader with any signal and set the filter mode to blacklist, half a belt get transferred anyways. When the signal is not present, the other half of the belt transferres the item

Thanks for the report! There's so much new stuff in 0.17 I hadn't even noticed that feature. Should be fixed now.

Nice. Cheers!