We do consider it a critical issue, yes. Unfortunately, we are sometimes forced to reschedule even critical issues to later versions; looking at our records, that is what happened in this case.
According to our tests, the issue affects all instruments that start exactly at the destination a transition timeline that does not have a destination region. This means that the only ways to work around this issue are to either add a destination region to the transition timeline, or to move the instrument so that it starts at a slightly different point on the timeline, and both of those solutions will result in the instrument beginning play at a slightly different time.
I suppose you could add a short period of silence to the start of the asset(s) associated with the instrument, and offset the instrument’s position by an amount of time equal to the length of that silence, ensuring that the audio starts at the same time? That solution might not be suitable if you need the instrument to loop, however.