Yes Steve, I think there is a Midi loop somewhere. But finally, I get around by adding another midi interface dedicated to the Arduinos managing the thumb buttons. That works fine but I must change some code in my project. Thanks for your help as this is a complex project and it not easy at distance to understand what I’ve done.
By the way I have a last question about MT Pro. Is it possible to change a common property for several translators selected ? For example, if I have 10 translators using the same Midi out port, may I select them (like to do a copy or a duplicate) and change simultaneously their Midi out port by another one ? Hope I’m clear but not sure 
Kind regards
Bernard
