Reality Composer - Edit in iOS - handoff denied

I'm trying to work with Reality Composer's (RC) key feature of passing files between Mac and iPhone, in order to view in AR. I've configured handoff correctly on both devices - and handoff is working in Notes, Safari - but in RC I keep getting the error "iPhone denied handoff request". What am I doing wrong? Thanks.
This has been broken for me for about 8 months too. Broken in Catalina, Big Sur beta 11.2 & 11.3 and Big Sur public release 11.1. Currently not working in Xcode Version 12.4 (12D4e). I provided feedback months ago. I can connect to my iPhone via handoff elsewhere and I can connect to my iPhone just fine when I run a build in Xcode. It appears to be a bug in Reality Composer.
Reality Composer - Edit in iOS - handoff denied
 
 
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