plc1 said "we need to talk about our relationship..." but plc2 was watching the hmi and didn't respond fast enough. Now plc1 thinks plc1 doesn't care any more so it wants to sever the comm link. But plc2 doesn't want to have to take on the whole project task execution, so it just lays around watching the hmi, ignoring the rantings coming out of plc1.
Side note: Plc1 turned 55 last moth and stopped having it's regular data purge cycles, so now it just overheats and cross talks at plc2 all day...