G'day @nightingale, thanks for the note. I can provide a save file from my backups. A bit more info about this - it's not a new bug in KSP 1.2, and I had the same issue with SCANSat contract pack missions in 1.1.3
What appears to be happening is that after accepting a mission which denotes a particular orbit, the next craft to enter an orbit of that body gets assigned to the orbit part of the contract, as with Minmus Orbiter in the image I posted. This carries through as well, when the next mission comes up requiring de-orbiting of the previous satellite before performing the multi-spectral scan, the contract will identify the vessel which was listed in the orbit category of the previous mission. I previously just ignored the error and put up with not achieving the optional parts of the contracts, however when it cropped up again the other day I tried again and again to resolve it through save file editing - to no avail. The only thing which worked was deleting the whole contract entry in the save file and starting it fresh.
Cheers