Hi WilliamQuigley,
I understand that you encounter the issue that the mouse doesn't scroll up or down in the site collection. To narrow down the issue, please share with us the following information:
1) Which broswer did you run into the issue, safari, Chrome or Firefox? Please try to use another browser to reproduce this issue. We would like to confirm if the issue is related to the browser.
2) You mentioned that only site you had this problem with. May I know if all the site collections can reproduce the issue?
3) Also, you mentioned that problem was the same as the other two messages on this thread. Please share with us the other threads to have a check.
Thanks,
Andy Sek