Thread:Extension talk:JSBreadCrumbs/Only visible on edit pane/reply

Well, that sure is weird. Are you doing any caching on your server? If you are using the file cache, or squid, or varnish, you will likely need to purge your cache after the initial install. You will, for sure, if you are using the file cache.

Check LocalSettings.php for:

If you have that, you'll need to clear your cache directory (usually /cache).

BTW, does this occur if you are logged in as well?