[Alan_SP]

I just found out that turning off xcache, i.e. not using xcache for datastore solved problem.

Any idea how to set this up to work with xcache and it's datastore?

EDIT: further info: I removed datastore prefix and it works ok now. I think you should try to include datastore prefix somehow.

This is the line in config.php I commented out:

// $config['Datastore']['prefix'] = 'forum_';

With this enabled, it doesn't work. It's not too big a problem for me, but there could be people who would use Xcache for more than vBulletin. So it works with xCache, but not when datastore prefix is used.