Reported in checkuser-l I think it's related to deploy of wmf.18 and thus should be a blocker of the train
Specifically, the bug is that IP range checks do not give results even if IPs in that range have edits. For example, a check on 37.228.251.79 correctly shows edits, so a check on 37.228.251.0/24 should show at a minimum those edits from 37.228.251.79, but it (incorrectly) does not show any results at all.