I decided to build some shops in Sanctuary to replace my worthless scavenging stations (seriously they don't really seem to do much of anything at at all) so I build one of each level 3 shop and go to re-assign my first scavenger to that store. When I assign him nothing happens. I try it again wait for the message that's it's been assigned, nothing. Get out of build mode and go back in. Assign him again and it finally works.

Problem is I go back to assign the rest of my scavengers and notice they are no longer assigned to anything. I look at my settlement stats and I have no food and my defense has been lowered due to defense stations having no-one assigned to them, then look at my plants and it seems ALL of my settlers got unassigned form their tasks, and are just wondering around including Mamma Murphy. I reassign them best I can remember, but now I cannot do anything with Mamma, she just complains about wanting to sit down even though I built her chair a long time ago. She refuses to go to her chair now and just stands there whining about her chair and refuses to talk to me until I build her a chair, which I cannot do!! WTF?