In the announcement for 2.3.13 it said:
However, after several days mine still shows 2.3.11 and there's no option to upgrade it, so what's happening with 2.3.13 for Cloud?
If you are a XenForo Cloud customer, your upgrade will be scheduled automatically.
However, after several days mine still shows 2.3.11 and there's no option to upgrade it, so what's happening with 2.3.13 for Cloud?