You turned one of the KMB stop to Citybus and place a new KMB one as replacement.  The problem is, that stop is occupied (by KMB 3C).  Either you also edit the relation, or you undo the edit if it's  taken over by mistake.

I have done a minor reversion on this at change 140661070.

https://www.openstreetmap.org/changeset/140661070