I noticed that on mobile devices, the cache is not getting dumped. So there is a very old page cached that is being delivered. I assume this is related.
I’m using mod_rewrite. What about you guys?
What I did to (maybe) fix this is delete the cache directory. If WP Super Cache detects that it doesn’t exist, it creates it. Mine is located in /public_html/wp-content/cache
Hopefully there was just a glitch and now that there are new files in the cache directory, they will automatically dump when they are supposed to. Time will tell.
Sorry for the delay in responding. I hope you were able to find a solution. I looked at the quickpay plugin and one of their recent updates include a fix for the gateway icons. Which version of their plugin are you using so I can look at the correct code to see if there is a conflict?