Plugin Not working

This type of issue is usually caused by caching issues. In addition to your own browser cache, there can also be conflicts with caching plugins and server-side caching. Do you have any caching plugins installed? If not, does your host automatically cache your pages for you (certain hosts, like wpengine, are known to do this)? If it’s a plugin, try deactivating the caching plugin and give the site a couple hours to stop serving the cached pages. If your host caches the pages for you, consider contacting them and asking them to disable that feature.

Good luck,
Justin