Where did you get the 1 million rows reference from? I am coming up against this same issue.
If I try to pull 8 tags, I got an error that I've exceeded the maximum count of 18750.
If I try to pull 9 tags, I got an error that I've exceeded the maximum count of 16666.
Multiplying tags * these errors, it looks like my max is 150,000?
Changing the "Max Count" doesn't seem to impact this. The only way around the error seems to be to reduce the number of tags.
I can't find any reference in the documentation on what the max count is.