I updated to CustomPress 1.1.1 today as per the update notification. The upgrade log said this was to fix an issue with custom fields not saving.
I've got some custom fields I use on posts (query_args that type of thing). I tried those today i.e. adding values to a custom field I previously created. That worked fine.
I think there may still be a bug though. I tried to create a new custom field within a post (needed it to do with Genesis framework I'm using) and the new custom field would not save. I added the new custom field and value. Saved it and it prompty disappeared. Tried it a number of times and I can't get the new custom field within a post to work.
Would you mind checking that out?