I was having issues getting emby installed on my odroid. No matter what I tried the actual emby plugin would not even show up in repo lists. I tried the official odroid lubuntu images as well as several openelec versions.
My solution was to check for updates before and after installing the repository. If I did not do it first I think it cached a dependency error and ignored emby. Then since nothing actually changed it would never fully check the emby plugin for compatability again. It looks like kodi checks md5 sums to see if there are any changes. I think it has something to do with the