Issue one
overprint cant be applied to groups, individual objects within that group remain unset to overprint, even tho the tick box claims its overprinting, it is not - this is misleading & downright dangerous

further more the color issue shown in the video , your objects should not do that , it again expands the risk for error , basically all the print sensitive setting in AI latest version have stopped functioning logically if you ask me & really up the risk for errors in print, never mind that going through all objects individually is tedious & unnecessary, prolongs the process & hampers work flow, it did do this in the previous iteration of AI, pls fix this urgently

Latest OS Mac & latest version of AI