Can't resume indexing

I paused indexing in Firefox and now when I try to resume it doesn’t work:

I click on the Memex icon in the menu bar (which is red with “pause symbol”) to open the menu, mouse over the “Indexing paused” entry with the red pause button (that changes to a grey “play” button upon doing so) and click the “play” button.

Clicking the play button changes the text from Indexing paused to Pause indexing for NN minutes. So clicking play gives a result that sounds like pause.

How do I re-enable indexing and make it start immediately?

Furthermore, by mistake, I managed to close the sidebar and now it won’t reopen/-appear.

Can you provide a screencast, i am not entirely sure about the behaviour.
How did you close the sidebar? With the X? if so then just reloading the page will show it again.
If you did a permanent “close” then going to the menu bar and pressing enable sidebar, and reloading again will work. (I know there is a bug we still need to fix)