Push Dataset PutTableInGroup and PutTable

Good afternoon,
Hope you are doing well.

I was trying to edit push datasets to do some testing for a new project and I had a python script for the "PutTableInGroup" and "PutTable" rest APIs so that I could add new columns to a certain table and/or change dataTypes in that table in a specific column.

I have done these tests before not so long ago (with both Python and a TRY_IT feature provided with the documentation) and I know it was possible to add new columns and change the datatypes, however, I am not managing to do it now ->I am getting an error 415.

Not only that I also noticed that there is no "TRY_IT" feature on the documentation Microsoft provides for the push datasets (as a last resort I would use this), for example at https://docs.microsoft.com/en-us/rest/api/power-bi/push-datasets/datasets-put-table-in-group and I am sure that it existed before since I have used it.

With that I used Python and went with Microsoft's example to PostDataset and then use PutTable to add a new column. I managed to create the dataset but PutTable is not working.

1. Is there a reason why TRY_IT feature not available anymore?
2. Is anyone is running into any problems with the rest API for PutTableInGroup and PutTable?

Best regards,