While testing new support for DV Fast Data, I ran across a particular
image that reliably generated a bit sequence that the MDMVM firmware
interpreted as an end-of-transmission. I dug a bit and discovered
that MMDVM only matches on 32 bits of the last data frame instead of
the full 48 bits.
See http://www.arrl.org/files/file/D-STAR.pdf section 2.1.2, item (6)
for details.