I know of one possible cause: MIDI polyphony. Each hardware synth like your Roland SD-50 has a maximum limit of the notes it can handle and sound at one time. That limit may be 64, or maybe 128; not sure about the SD-50. You might think that BIAB could not generate that many messages to overwhelm a hardware synth, but it can because some patches require up to six messages per sound. Multiply this by many notes in a chord, and many tracks of MIDI instruments including a drum kit, and it's easy to hit the limit. MIDI "on" messages must be followed by MIDI "off", but sometimes those are not received. It's why music programs using MIDI all have a "Panic Button" to turn off MIDI.

To test this, mute some tracks and see if the problem goes away.

Other possibilities include system memory (reboot) and corrupted BIAB files.

EDIT: Just checked and your SD-50 has 128. That's good, but sometimes not enough.

Last edited by Matt Finley; 02/19/16 11:49 AM.
BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.