
Yes, that is expected and this is a known limitation.
The trigger "When someone responds to an adaptive card in a chat or channel" only fires for adaptive card responses in chats or channels that the Teams connection account used by the trigger can access.
In the scenario where it works, the Teams connection reference is your personal account and the card is sent to yourself. In that case, the 1:1 chat is visible to your account, so the trigger fires. When the card is posted to another user’s 1:1 chat with the Flow bot, that chat is not accessible to your account, so Flow B cannot “see” the response and the trigger does not fire.
What you can do:
Use “Post adaptive card and wait for a response” in the same flow, then call Flow B via a child flow or HTTP if needed. Or merge Flow A and B.
OR
Post the adaptive card to a channel or group chat where the Teams connection account is a member.
Let me know if it helped!