I am guessing, and not an expert here. This may not be a definitive answer, it is just my thought process.

I guess its the first inversion of D major?

D F# A - D Major F# A D - D Major, first inversion

Since F# to A is a minor third, that to me explains the F# minor. F# to D is a a raised 5th, aka augmented 5th, and I am pretty sure + is the symbol for augmented.

Ok after writing this out, I think I am correct, but please, anyone else, correct me if not.

Seems that the software is thinking of the first inversion of D major as F# minor with an augmented 5th. Weird but I guess not technically wrong.