Using template with defined enum data type causes pattern to lose field

[MattMills]

bug_case.zip
I've attached a zip file containing a test file and pattern for reproduction.

Demo screenshots:

The test_data field gets dropped from the parsed data if it is used via a template variable, if the template variable is removed and replaced by parent.parent.head.test_data, it works as expected, also, if the test_enum type is replaced with u8 it also works as expected.