MongoS clients not seeing databases after config server change to CSRS
There were no errors during the migration process. BUT a NEW dbpath was used so the initial config server didn't use the existing details but in fact created 'empty' details in the new dbpath.

Basically when doing the migration, the first cfg server does not change it's dbpath nor it's port throughout the migration procedure. Personally I found this unclear in the procedure, especialy when you are migration from SCCC to CSRS and using WiredTiger.