Or perhaps "Can't set 3, 5 or 8 as a filter until researching Number Addition".

It'd be nice to have a way to filter out the giant pile of 3s, 5s, and 8s you get from decompiling uranium products before researching Number Addition - or at least to have Number Addition indicate that it gives the ability to filter numbers other than "2".

As a work-around, the filter can be set in sandbox mode and put into a blueprint. Unlike recipes, filters can be imported even if they are locked.

It might also possible to set a logistic request that way by blueprinting a request group in a constant combinator, though I haven't tried.

This issue should be fixed in Version 1.3.0 ^w^