Where can I submit an issue detected in your plugin?
In multisite installations isn’t possible to add more than one theme or plugin in the list. When you add a second one the first one is deleted from the database.
The issue is generated by your plugin: Envato Market.
You can add whatever you want, the plugin just save the last plugin or theme added. The issue is not related with multisite compatibility. I tested it in two installations.
This is public forum and I am not employer of Envato. If is working on 2 different multi site than problem is not in plugin it is something else.
That is problem in plugin it would work on any multi site simple logical thinking.