Cannot Publish/Save as Draft post with lots of HTML code in the HTML widget

Hi,
I have troubles publishing post when added (large) html code to the HTML widget.

The code is from Jupyter Notebooks and when pasted in the HTML widget it gets rendered just fine in the backend. The problem starts when I want to Publish or Save as Draft. After pressing the button the spinner start spinning and the green bar at the top start pushing right but after its done the Publish button is still green and the post is not saved.

This is the sample of the html I need to show in HTML widget: https://academy.datamasters.ai/extras/ML_balancing.html

I managed to get it using iframe but I have problems with the links in the page so I want to get the raw HTML in the page instead of iframe.

Any pointers or suggestions are greatly appreciated.

Have a great holidays, btw ??

Thanks,

S@