Theme My Login button not working

Hi all. I have a weird issue that has just started manifesting itself. When I go to our clubs website members login page I can enter username and password, but when I go to the login button it does not work and the cursor does not change, it remains as a pointer. This is now happening randomly for users in both chrome and edge. I have checked that XML/Java is enabled, and on my PC whitelisted the site, I have also cleared the cache in both edge and windows but still nothing.
Any ideas or help ppreciated.