Cache details page/Metrics: The 'Current number of entries' is not shown properly.

The 'Current number of entries' in Metrics tab under `Cache details` page is always 0, even though there are entries in the cache.

The same refers to to `Memory` section. No matter how many entries are in the cache, it always shows `-` signs.

UPDATE: the same refers to Global Statistics page. The current number of entries and number of entries in memory is always 0 (see screenshot).