Open custom UTType from messages.

I've declared a custom extension in my plist for "Document types", "Exported Type Identifiers" and "Imported Type Identifiers". I'm sending the file via messages with the right extension, the file with custom extension shows in messages when received. However when I tap on it in messages nothing happens.

I know UTType is a fiddly subject, this question has been asked many times before from different angles. Instead of me sending my plist etc does anyone have a working project that exports a custom file extension that is openable in messages when tapping it? If so any possibility to share this project in Git so we can have a master example so devs don't have to go thru this painful process?

Open custom UTType from messages.
 
 
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