I have a DN lookup field called "Account DN" on my page, set to use
"container" as the "Object Selector Type"

When I click on the "search" icon for this field, I get the following error:

"Account DN: error occurred while treating property: misssing or bad
container selector properties. Error Message:
Account DN: Error in JUICE.ContainerPopion._additems(): Service returned
error. Return code=500, Message=Error encountered while executing the
service lookupcontainer: No root container defined., Throwable= "

Now, it might seem like the "no root container defined" is a smoking gun,
but I've got my root container defined... On the User Entity that this field
uses as its lookup key, and for the UserApp generally.

I've tried defining the root on the User entity as %user-root% and as a
hard-coded container reference... o=data

Neither worked. The lookup does work if I use "paramlist" as my object
selector type.