exhibit disappeared

I'm working with a group this week who are using a server-installed omeka instance together (18 people total). We just had an exhibit disappear, and no one deleted it. Another exhibit disappeared on Monday, and I figured someone deleted it accidentally, but now I'm not so sure. I've installed Omeka before and haven't had this happen. Is it possible we are overwhelming it? Is there some known problem that I can fix? Thanks!

Do you know anything about what led up to the disappearance? Was someone (or many people?) editing it? Or, was there no activity, and they just disappeared?

I am not sure, but it's possible multiple people were editing. We have over a dozen exhibits being built now, and there are certainly time when people are working on exhibits at the same time. Of course they aren't all disappearing.