The logs show that the first repeat triggers all 20 times before moving to the second set of repeats which triggers once, before stating "Action: END-REP (waiting for next)" and not repeating again. (Note that the repeat time period is a few seconds only for testing purposes)
Hoping someone far smarter can point me in the right direction to fix this rule.
Yeah, appears to be a bug with that. For now, a workaround is to use two rules, with only the second repeat in the second one, and run that from the first one. I'll find the problem for the next release.