might be 2 separate issues.
so ansible is not running as a leader but it freezes too? when it freezes, what does it look like, no response to grid presses? are outputs still being updated? is the behaviour the same when it’s frozen after power cycling? did you ever experience a freeze upon powering up when it didn’t previously freeze during a save?
i doubt faderbank firmware version matters. “before testing without 16n” - so you have a scene that uses FB ops but you test it without FB connected?
totally wild guess: perhaps with the latest update there is more being written to flash, and flash operations block i2c causing the bus corruption. weird that ansible would freeze while not being a leader but possible i guess (and sounds like you also control kria from tt).
another wild guess: is it possible that ansible switches to leader mode while in preset mode? also might be a good idea to disable i2c temporarily before saving to flash and enabling it after.
i would say this sounds to me like the bus is not stable in general. try using shortest cable possible to connect fb and use the correct sequence of powering (iirc you have to connect fb first and then power it? not sure, it’s in the fb threads somewhere). also could you try disconnecting txb (so, just leave tt / ansible / jf connected) and see if you still get the freezing issue.
yeah, we never found out what caused the issue on teletype, and without a screen i don’t see any elegant way to add a similar safeguard we did on teletype without confusing users. one thing that seems common to both scenarios is that there is something being written to flash outside of saving presets - on teletype it was the last screen used (which we since removed), on ansible it looks like it updates the follower config? perhaps there is some really edge case scenario where flash becomes corrupted or the fresh byte gets accidentally overwritten. perhaps we could add an extra guard, use a longer marker or have more than one marker… not sure what else we can do with this issue to be honest.
final note - sorry to hear this, it must be super frustrating. i assume you’ve seen you can also backup to USB / computer? not a proper solution but at least not as painful as losing your complete work…