I'm getting the same issue. It appeared after Python in Excel had worked fine for a couple of days. I tried all suggested mitigation, but to no avail. I've contacted Microsoft support over several days, was given the runaround, and finally they offered no help whatsoever on this. They advertise the feature, but the user is left without service and with a non-working product. The #BLOCKED! error came with an "explanation" which read "Limit exceeded", however, there is no further information on what exactly those limits are, why these would be triggered, and when these limits reset. Microsoft help were not willing to investigate the error further, or explain how the #BLOCKED error related to "Limit exceeded". In fact, in their adverts it says *nothing* about a limit, see pic below. As a paying consumer, I find this very confusing, and I think I might have wasted a lot of my precious time on this feature.
Shame on you Microsoft!