I am upgrading my whole site, I moved everything to the new dev server, and everything works except that K2 is not seeing the images located in the: /media/k2/items directory.

 

All the images are there, yet K2 doesn't seem them anymore.  It seems them on the old server, not the new one.

Have you also copy ther cache folder?

 

Check K2 information tab and be sure you have mb_encoding on the dev server.

I use akeeba backup and kickstart to move sites and it works well - it get everything at once