Me too, I am running DCS 2.9.13.6818. I have tried it three times now with same non result. First time around I skipped to the first refuel, completed the CAS mission, refuelled and then completed the case one but a line of F18 in Baltic Dragon livery (cool by the way) were blocking the taxi in and the marshaller just gave me the stop signal and there was no mission complete message. The 2nd and 3rd time I skipped to the RTB part of the mission and got cleared for a case 3 recovery, landed but with no marshalling and no cue to say mission complete. The last time I left the game running until I flamed out but again no mission complete message.
I ended up just editing my logbook lua file to say I completed it (https://forum.dcs.world/showpost.php?p=2180489&postcount=740).
I also could not contact the tanker on the way home until I formed on his wing and the dialogue was triggered, at this point the tanker appeared in the comms menu.
I feel for you BD, as all these bugs are created outside your control with ED updates yet you are the one who has to clean it up. Love your work man.