Annie, I am currently in a chat with support for another access issue and I asked them if your issue might be connected. They suggested this: “It may be a browser setting or they may need to clear cache, in that case. I would also make sure that they test navigating to the site on their phone off of their wifi, so they can test their network cache and make sure that it’s not a weird firewall/adblock/antivirus issue.”
I don’t know if you are accessing through your phone or what, but I am just forwarding the suggestion. Let me know.