strange liquid thread behaviour

Just tried starting a thread on Brent's sandpit. When I saved the
thread I got a blank page. The tab for the discussion has gone to blue
but there is no new thread. I tried two more times with the same
behaviour. There are 3 new threads in the recent changes logs:

(diff) (hist) . . Nm  Thread:Width of the collapsed navigation bar
(1)‎; 09:35 . . (+260) . . Kruhly (Talk | contribs | block) (New page:
Hi Brent, Nice navigation bars. I read somewhere that there is a bug
in Firefox that causes the collapsed table (navigation bar in your
sandpit) to shrink its width in comparison to the ...

but none show up on the sandpit discussion page.

Any thoughts?

Cheers

Rob