Block breaks when realnames are calculated for the first time

Firstly, thanks for this awesome module. It does just what I've been looking for.

Unfortunately when I run the realnames calculation the first time, something happens in the blocks admin which makes almost all blocks disappear from the regions they have been set in, and reappear in the disabled section. I've tried with a variety of settings in Realnames, but no matter what, once the names are recalculated this happens.

This affects the blocks admin page only - the site pages still looks normal with the blocks all in the right place.

The other thing that happens is the theme on the blocks page, which is a custom theme on that page, defaults back to the standard drupal admin theme. I'm not sure how helpful a screenshot is but I'll try to attach one.

What other information would be helpful?