The two first troubleshooting steps I would recommend are,

Log off, remove your account and log back in - You can do this by signing out of the Chromebook and then on the login screen next to the username is a dropdown arrow. Click that arrow and there should be an option to remove the account. This clears any temporary data that may be corrupted and causing issues.

Disable uBlock - This is an ad blocker the district uses and can very rarely cause issues, you can disable it for a specific website by following the instructions below,

Click on the puzzle piece in the top right of the browser and then uBlock Origin

Then click the big blue power button and then refresh the page. (The button will go grey to show that it is disabled)