If you can provide details of the actual commands being sent by behringer i’ll try to replicate. Don’t tell me what you think the behringer is doing, use a midi monitor or daw to see exactly what is output upon a button press
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Also try this with just one master pickup machine too, to get away from the possibly related issue of badly presented status re slave/master, to see if it helps
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Test using an explicit channel too, to see if it changes anything, ie use 7 aot 11,just for completeness