We’ve noticed an issue on OCTO when the first cross-JVB participant experiences poor download quality. However when the next participant joins after it fixes the poor quality download for the original cross-JVB participant. Like its not getting the selected endpoint event properly.
However, saying this we have been messing around with the selected endpoint events in our custom code. So may be something there causing a problem.
Anyway, do you have a standard jitsi UI URL with OCTO enabled at the moment that I can do a quick test on?