UpdraftPlus Update is stalling out

OK, I’ve found what might be the problem. I have a couple dozen sites I manage, and found that the problem was isolated to a particular server on one of my hosting accounts. It turns out that the php version for all those was PHP 5.5, and websites on other servers are running PHP 5.6. When I upgraded to 5.6 on those sites, the UpdraftPlus plugin would then update. Accomplished this on two sites so far, both success.