load collection not working on en.wikibooks

I tried it today, and the "load collection" feature doesn't appear to
be working on en.wikibooks. I've tried with several saved collections,
and none of them will load. I don't remember the last time I tried to
do it, it may have been before the flaggedrevs extension was
installed. Any ideas on what might be causing this? Is this error
happening for anybody else?