It seems that when I'm trying to build in this settlement, the shared materials will not show up. I.E. I was trying to put in a few lights, all of a sudden it showed I had no materials when just a second ago it showed I had hundreds of each. Sometimes switching to a different item will help, but only for a minute. I'm not sure if it's just an issue with building powered items here, because I've only noticed it when building lights.

Update: not just powered items, just happened with steel.