Minor flat 5? That's a diminished triad!
But in all seriousness, though I'd call it °maj7, I've seen plenty of use for that chord. Built on the 4th scale degree in major, it makes a nice minor-plagal-ish sound similar to that of ivmaj7 [that's to say, Xm(maj7)]. It can function also very similarly to a fully diminished chord: iii7 to ♭iii°maj7 to iim7 sounds nice in a functional jazz context.
Rearranging and respelling the notes, one finds a potential reason for its functional sensibilities: B(♭9)! The chord contains a major triad, and that can give this set of notes a sense of stability that diminished seventh chords lack.
Another cool thing: This chord can go really well with the G harmonic major scale [G A B C D E♭ F♯ G], and you can make some beautiful sounds out of that.
Overall, the chord seems much more closely related to the diminished tonality than the major seventh tonality, but adds a bit of stability and brightness to an otherwise tense sound. There's no "right way" to resolve this chord, but the above are some ideas on how one might get started experimenting with it. If you like the sound, who's to say you're wrong?