I have never been able to successfully engage relatch mode. When it is on, it simply stops taking in note information, and I often have to cycle back to blank and then ‘hold’ mode to start a new arp chord.
Also still get hanging notes that have to be killed by cycling through hold and relatch back to empty.
FWIW, I am using a Prophet 6 in local off as the controller keyboard, though I get the hanging notes most often on it and my Roland SE02.