Problems with the old Aeon file, converted from v2 to v3, prompted me to create a fresh Aeon file. This new file is approaching perfection, but a few glitches remain.
I’ve always used colors in Scrivener’s Binder differently than I’ve used colors in Aeon’s Events. Not a problem in the bad-old days—Aeon simply created a new piece of metadata, and I relabeled it “POV Character (color)”.
I can sorta do this with my fresh Aeon file, and it syncs once, but then disables itself. Here’s Sync Properties behind the gear icon:
Note that Color is disconnected. That drop-down menu shows this: 
“POV Character (color)” is from an earlier attempt that now fails. Within Scrivener I go into edit custom metadata and delete “POV Character (color)”. Note the “-” sign to delete:
This wipes out the metadata type, and all the data associated with it. Then it’s back to Sync Properties in Aeon, but this time I select Create New. Instantly Sync turns nearly everything orange. When I sync, Aeon pushes all the colors down to Scrivener (perfection). The moment it completes it puts this warning into the Sync window:
And that’s it. Color syncing is killed, unless I wipe out that piece of metadata in Scrivener and start over.
This isn’t a death sentence for my project. I’ll probably add another scene or two, but I can always manually sync this case. But it’d sure be sweet to get this working.
Thanks a million for your insight into why this happens.