Yes, since I posted that thread I have had the same issue with my grand master vampire. He was able to use the clothesline and then suddenly couldn't after returning home from visiting another lot. If I cured him he was able to use it again, so it does seem to be a vampire issue. Thankfully I didn't have to start a new save again as I found that moving his household to another lot and then moving them back into their home again through manage households seemed to fix it. I also placed a copy of their home over the original before moving them back in, but this might not have been necessary. Hopefully this will work for you too.
