This article is useless... its headline claims paperwork issue, but nowhere in the article does it talk about why all 40 went to Trump....
Facts and details would be nice.
As near as I can tell, the RNC's only delegate apportionment rule is "The State delegations must follow the rules of their state GOP."
So, the Utah GOP rules say that if only one candidate survives, he gets all their delegates. Simple as that.
There was a minor bruhaha with Alaska and DC. Same state rule, so the same result.
Note that neither the Trump campaign nor the RNC wrote that rule. Those delegates must follow their state party rules for delegates.
It's why some states are "winner take all" some are proportional, and some are a modified proportional rule. The state party decides the rule.