- Open the console
- Select the PA frame
- run this command: cf setlinkedref none workshopitemkeyword
Turns out that if you move a PA frame using the workshop system, it'll link the PA frame to that workshop, rather than the nothing it's supposed to be linked to. This can be caused by something like Movable Power Armor, but there are probably other mods out there that'll do it.
Anyway, if the PA frame is linked to a workshop, the crafting system will look for resources from that workshop, rather than from the PA station/local workshop that it's supposed to. Most of the time you won't notice, but if you end up accidentally linking it to a workshop outside of your supply line network, crafting will appear to be broken. Manually clearing the link with the console command I wrote above will fix the frame, until you move it again anyway.