offset=42492

That's it. mp3tofid assumes it can find the start of the first mp3 frame in the first chunk it reads.
The chunksize is 40960 (#define INPUT_BUFFER_SIZE (5*8192)) in scanmp3.c.

Your mp3 seems to have a much larger id3v2 tag than I then the ones I tested with.

The lazy workaround to this bug is to increase the buffersize and recompile.

Unfortunately I will not be able to help, as I am packing for a three week trip to Asia.

Pim