Error trying to create Comprehend Flywheel : ModelType field shouldn't be provided if ActiveModelArn is provided

I've created a custom classifier from an S3 bucket. I want to create a flywheel so I can introduce new datasets. I'm using the console, not cli. I created an empty bucket in S3 and I choose that bucket for the output. For IAM new role I am Root. Create goes through the IAM part and then back to Create with the error message FLYWHEEL_UNEXPECTED_FIELDS_PROVIDED_WITH_ACTIVE_MODEL: ModelType field shouldn't be provided if ActiveModelArn is provided.

I have not found that message on a google search or anywhere else. My original input file was a csv file and I chose split to divide 10% as test.