Unable to update the auto generated schema in Google Auto ML data set

Question

I am setting up a prediction model using AutoML Tables. Here are the steps that I have completed.

1. Prepare a csv file with relevant data(4 fields).
2. Preprocess the data file.(Remove records with null values and repetitive records).
3. Create a data set by importing the processed file in the import step . In the train step, I see the auto generated schema.

I am unable to edit that schema(specify the target column or modify the data type of a column).

Pls advise.

I encounter below errors

1. "Schema update failed - The attempted action failed, please try again"

2. "Failed to update schema - Schema update failed with errors"