Unfortunately, the Instagram API (the system that lets different software communicate with Instagram) is not providing the necessary information to display these messages. If you see a message saying "Unsupported message - View on Instagram", it's not a failure from Missive, but it's the actual message Instagram is sending.

There is currently no solution to this problem. It's up to Instagram to update their API functionalities. This is a known issue that has been reported to Meta by other developers for a long time.