In your Data Studio editor, click resources --> manage added data sources then go to edit connection.
There is an option to use _PARTITIONTIME as the time dimension. I suspect Data Studio has picked up this magic field and tried to use it as a time datatype and there is some incompatibility going on. I think this field is really metadata so shouldn't be used. Data Studio should really ignore it and not try to be too clever in finding your fields and inferring their usage & type from their names ( Although, mostly that is helpful ).
Unticking that option, clicking back to the report with Done will let you resolve the issue.
