I have the message:
"The security ID did not match. The request was terminated to prevent a security breach. Please try again." even after refreshing the browser page!
while the joomla login menu link is working properly.
How to operate this module?
In SCLogin, can you set the Advanced tab > "Caching" setting to "No caching" and try again?
If that does not work, can you try deactivating the System page cache plugin to see if there's any change?