DMN Validator is raising false positives for errors on type resolution. It looks like it is happening since the following commit was done:

https://github.com/kiegroup/drools/commit/9e2fdc4b5e83bb9b5350a37fd89dab8f38cc8582

The problem is that the .toString() call on the QName will return the full name, including the namespace:

tDailyPrice

And that will always fail the constraint:

ItemDefinition( name == $typeRef.toString() )

I believe the correct would be to change the constraint to:

ItemDefinition( name == $typeRef.getLocalPart() )

But we might also need to check the namespace somehow.