Hi Ruth.
I'm going to try to reproduce your issue on my local server, thanks for the list. On the meantime, there has been a report about Post Types Order and Views, here:
http://wp-types.com/forums/topic/edit-view-slow-and-not-updating/#post-61354
It is known that some plugins that try to modify WordPress queries can be incompatible with Views.
I read that when using TwentyTwelve,even with the listed plugins activated, Views renders the texts, right? Could it be a theme-compatibility issue? I see in your site (source code) that you are using a custom theme,maybe created in-house. This could be related.
As I said, I'm going to replicate your environment using the default theme and see if I can reproduce your issue. Then I will come back here and post my findings.
Please let me know if you are satisfied with my answer and in there is anything else I can assist you with.
Regards,
Juan de Paco