Discovered a tricky-to-diagnose bug today. I have an image_advanced field that I'm using to create a simple gallery, and it's got close to 200 images in it. Adding and working with that many images is fantastic. However, recently the person who works on that page reported that when she made a change to the content field (not the image_advanced), all of the images disappeared.
I wasn't able to recreate the issue until just now. It turns out that if you save the page before all of the images load into the image_advanced metabox display, it saves the page without any images at all, and the next time the page loads, they're all gone.
I'd say this is a fairly major issue, but maybe that's the expected behavior? I'm not sure. I guess my solution would be... when saving, check if there's an image_advanced. If there is, has the content of it loaded? If yes, cool, overwrite what's in the DB, because changes may have been made. If it hasn't loaded yet, don't overwrite anything, or overwrite it with whatever it's currently requesting (same result in the end).