XS Max iMessage error: "Number not available. Which number would you like to send the message with?". I receive this error when sending a text that came in from another number when text forwarding is enabled.

We have several devices sharing different iCloud and iMessages and iTunes. The problem is on the XS Max. When a message is received from the other devices, the XS Max cannot return an SMS text using the alternate number. It gets an error. The error says “cannot send from this number. Must use your primary number.“ The primary number being the number of the XS Max, not the number that was texted by the incoming text. The iPad Gen3 is on the same iMessage ICloud ID as the XS Max. The iPad sends texts from the correct number (the originating incoming number). iMessages (blue texts) still work as normal. The problem is responding from a different number would cause confusion to the person texting the original number.