unfortunately by transposing all tracks of the midi file you have transposed the drums along with the melody tracks of the midi file, and now all the drum sounds will be mapped to the completely wrong notes.

to transpose a midi file you need a two stage operation. Now transpose track 10 in the opposite direction with the same number of steps as you transposed all the tracks originally.

Then you will have a correctly transposed midi file to save.

You could of course transpose 15 tracks individually, leaving out track 10, but the 2 stage operation is probably rather easier.