New wbsites being ignored

I have a strange situation where new websites that are added to the website list in Piwik are not available in the list of websites when managing access rights.
I can force them to display using the search button (however I only have a few and they are in alphabetical order normally) and when I set user setting (assign a user) for remote tracking, the remote tracking WP plugin also does not see these sites.
Any ideas why this is happening and how I resolve this ?

Not really an idea. If you delete the piwik/tmp/cache/ directory does it help?

HI Matt,

I removed the contents of piwik/tmp/cache/ and the list hasn’t updated (same list seen in the Piwik User settings and WP Piwik plugin). Its strange because those 3 sites that are missing are not the last 3 but in the last group of sites so no particular pattern. I did notice that one of the domain prefixes was incorrect “wwww” instead of “www” so I modified this, however it didn’t resolve the problem.

Any ideas what I could try next ?

Interesting. Since fixing the prefix on that first stie the list of websites still fails to update in the user and plugin screens, however auto configuration for WP Piwik is working, so it find the site OK and tracking is live. Strange.