Some older pieces of gear (particularly Roland gear) interpretted the MIDI spec differently. They treated the CONTINUE message as the first F8 beat clock i.e. they start clocking ahead immediately after receiving the CONTINUE message. This results in the external sequencer being 40 ticks ahead of Pro Tools when played back from anywhere other than the session start.Since Pro Tools currently doesn't allow you to specify a "MIDI Beat Clock Offset", the only workaround is to always start playback from the beginning of your session. This is not a bug in Pro Tools, but may be addressed in a future release of Pro Tools.