I am active mainly in two sites: main SO and Russian.SE - including performing reviews. Normally, when I click the
review link, I expect to see 6 queues: close votes, reopen votes, suggested edits, first posts, late answers and low quality posts. They may appear in different order based on what's available and which ones I exhausted for the day. On the main SO site there are always 6 queues. On the other, on Russian.SE sometimes I see all 6 queues (possibly with 0 questions in all of them), but sometimes some of the queues are missing. Below is the screenshot from this morning, where only three of the six queues are available. As that site is still in beta and doesn't have a lot of activity, most likely, the missing queues have 0 questions, but then the ones showing also have 0 questions, so I'm a bit confused as to what's happening here.
EDIT I believe I got to the bottom of it now. Apparently, the screenshot is of the review for meta.russian.SE - which has 3 queues. Once I went back to main russian.SE and into review there, all 6 queues were available again.