When it comes to caching on a site (or server) we recommend checking the following:
If a cache plugin is installed, temporarily disable it and see if the issue remains while it's disabled.
If the issue no longer occurs while the cache plugin is disabled, that suggests the issue is cache related.
You can run a quick test by checking the site in a Private or Incognito tab in a browser after disabling the cache plugin. This ensures you're viewing a fresh (non-cached) version of the site.
That being said, this doesn't mean a cache plugin cannot be used on the site. This test just determines if the cache plugin is contributing to the issue.
If a cache plugin is being used, the next step is to clear the cache on the site.
There are a few different terms for clearing cache. Some plugins will refer to it as clearing, flushing, deleting, etc.
The key is to remove the currently cached information. So use the clear, flush, delete, etc. option available.
Once the cache is cleared, check again in a new Private or Incognito tab in a browser to see if the issue remains.
You should be able to run WishList Member with a cache plugin or caching on the server as long as you avoid caching pages when a member is logged in.
Most cache plugins will have a setting to help with this kind of thing. Or, most servers/hosting providers can make these kinds of adjustments.
Once adjusted, the site will only deliver cached pages to non-logged in users.
If a member is logged in, it ignores the cache.
You also do not want to cache any registration pages.
To avoid any potential issues, most cache plugins or servers have a method for you to exclude pages from their caching.
Adding the following WishList Member pages as exclusions should prevent issues:
Please be sure to clear the cache in your cache plugin/browser before any testing.
Additional details can be found in the Caching Knowledge Base article.