No Instrument change cautionary accidentals

I can’t see in a Player’s Part (Altosax/Flute) the Instrument change cautionary accidentals
between the Flows. No Sign, that the Altosax Player has to switch to flute for the next flow.
What’s the Problem?
(within a flow, it works well)

My observation is that instrument changes across flows are not treated as an instrument changes at all; they are treated as if the new flow simply starts with “an instrument.” It appears to make no difference whether that instrument is the same instrument as the one that ended the preceding flow or a different one.

Not only are cautionary accidentals missing, but there are no change instrument notifications in the parts (though neither the accidentals nor the change warnings are time consuming to enter manually.)

rosn, there is no connection between the musical material in each flow, so if one flow ends with the alto sax and the next starts with the flute, there is no warning for the player that he/she needs to change instrument. We plan to add a label in this situation, however we won’t show an additional key change: the new flow has no connection to the old, so it cannot show a “cancellation” of the key signature at the end of the previous flow.