I created memcached store instance and added store mappings to the store instance. All look good after setting it.
But after days, I go back to the cache configuration page, and find the memcached store and store mappings are all gone. The primary store is set back to the default file cache.
I am using Moodle 3.5.5+.
Hope any one may advise me and give me some clues for the possible reasons for this issue.