Woah! it's working when this option is disabled I tried this before aand it didn't work – did you change anything? Thank you so much whatever you did!
so, a few days later it's still working fine with the verison you linked (and "send all in group" disabled), so I think this thread can be closed. thanks again @joaomgcd and also thanks for taking on Tasker – Tasker is (togetehr with your apps) the reason, why android is so great