Everything indicates that it can not set a detection point in the zone DRS. When the detection point is for zones it works perfectly. I hope that the ISI will take into account and fix-modify the system DRS on the tracks in rFactor 2.
I don't really understand what's wrong. We've done multiple tracks with double DRS zones and separate DRS zones (per F1) and it worked fine. *If you're expecting it to work with the detection point somewhere in the middle of the DRS zone, what are you basing that on? I don't think F1 has ever done that.
It makes impossible to setup DRS rules for DTM 2016 season. The detection point for all zones is at the s/f line and as you say it happens one of drs zones is along s/f line, too. Pity.