It appears that in the "TA-microsoft-windefender"-addon something is missing that causes warnings in the search-log but more important, it does not do what it is supposed to do. The problem is contained in ".../default/props.conf"
In line 25 is stated:
EVAL-Feature_Name = case(Feature_Name="%%802",
Which is obviously an incomplete eval-expression. Does anyone have sorted out how this full line should look like?