[LAU] Sysex with Jack MIDI

Hi, I try to understand why sysex go through jack MIDI sometimes, and sometimes they are lost. I am aware that jack has a limit for the maximum message size per period, but I am playing with program dump of my Nordlead which are only 139 bytes -- definitely not huge. I am running jackdbus with a2jmidid, through Catia. My system is Debian + kxstudio. When I try an application with native jack MIDI, such as Reaper (with jack backend) or MuSE, I can record sysex successfully, but when I play it, it never reaches the hardware. With applications using ALSA sequencer (tested with qtractor and Rosegarden), I can record and play successfully sysex using ALSA. However, I cannot record nor play sysex when connecting jack MIDI ports instead (jack MIDI wrapper ports from a2jmidid). Is this the expected behavior? Are we stuck with ALSA when we are dealing with sysex messages? Bonus question: is it possible to be warned when jack is dropping sysex messages? Thanks! -a.