Players listed at Running Back no longer seem to be improving their pass blocking if they're a 'boom', and it is instead slowly degrading. It seems that this has been switched off as one of their core skills?

Bump. I still think this is an issue. Pass Block should be a native skill for RBs.

RBs should be generated with a uniform distribution on their pass blocking skill, either they have it or they don't. You should be able to find 100-rated future pass blockers at the RB position, and you'll just as likely find 0-rated pass blockers at the RB position. If they don't have any blue, though, just like other attributes they won't outside of their volatility bringing it up.

If you have a specific player in mind that improved all attributes but pass blocking let me know and I'll look under the hood to make sure pass blocking in not developing differently than any other attribute, but I don't immediately have any thoughts as to why that would be the case. There are a few attributes like that (kick holding for QB's, long snapping for C's and TE, etc) that are completely random uniform distributions regardless of the players' other attributes.

PB is not considered a native skill for RBs in terms of developing it if their vol pushes their atts up, and will instead slowly decay over time. In congruence with this, it does not show up as a skill for RBs under the default weights. You can look at any 'boom' RB and see this trend.

Just one example off hand:
https://private75.myfootballnow.com/player/3451