Thanks for checking @BLUEFROG. Good to know it’s not just me. I think the x-callback is an issue when switching apps (from DTTG to Shortcuts), but apparently @sven.luetkemeier doesn’t.have that problem. I am using an older device and Shortcut might somehow stall when memory runs low or something.
I’ve worked around for a second time and used split screen to view the shortcut on one side of my screen. I then select a record in DTTG on the other side of the screen and run the shortcut. With the callback I managed to get a UUID for any record. I’ve subsequently managed to setup a workflow to start renaming records in DTTG3 with Shortcuts by extracting the UUID from the callback.
Thanks @sven.luetkemeier! It involves some work, but I think this is usable work around while the DT staff thinks through if they can get DTTG to share the UUID together with the content. This workflow also allows me to setup complex OmniFocus tasks and insert the UUID DT URL-scheme to reference an accompanying file.