I use the latest versions of firefox and expressvpn for linux but the vpn won't work with firefox?

Hi. I run Pop_os 24.04 linux and have run the latest updated firefox for linux and the latest expressvpn for firefox and am not able to get firefox to connect with the vpn "on". It did work a week or so back but not now. With the vpn on, firefox takes at least 15 seconds to load. I've run the troubleshoot mode and it didn't help. Are there settings on firefox that could be the issue or is it a vpn problem? Thanks