We have reported that on their 10.51 env. they are not able to import MS cumulative updates.
4495257 (SQL Server 2016 SP1 CU15)
4013098 (SQL Server 2014 SP2 CU5)
I will upload a complete list of KBs shortly
I performed a test on our 10.51 lab by importing MS offline catalogue along with mf-connetor ms patch supplement content and I am still missing the 4495257 patch.