Is a way to make a custom sort the K2 attachment and rename after upload? I would think this would be a required feature.

Hi. Our development team will be informed about your request. Thank you for your great feedback.

:cheer: Thank you a lot this is very important to me. I develop lot of sites for local Government institutions. In this site have lot of attachment for official documents in any items, sometimes they need to make a custom order but now is not possible, or they have typed wrong title which cannot be rectify only if delete and upload again. It very nice how is solved in extra field. I hope that soon made.

Have someone solved the attachment ordering ?

Im struggling with this exact same thing too...

anyone got any luck with this?

Unfortunately you will have to wait for K2's next version.
You can use extrafields as a workaround. Extrafields can be rendered separately and ordered so you can have the same behaviour.