I'm using media_browser_plus 7.x-3.0-beta3+8-dev and media 7.x-2.0-alpha3+100-dev, and they don't seem to work together on uploads. I've had them work together on earlier versions of both. I cannot specify both the media browser plus folder and the list of files. I just imported using thumbnails plus from the content/file display. The files ended up in the correct place, but media browser plus doesn't list them in thumbnails plus and they are not visible as library content. It looks like media_browser_plus_form_file_entity_add_upload_multiple_alter is making the submit process skip some steps. The media browser plus code may have been depending on a side effect in a previous version of media. The "right answer may involve changes to media, media browser plus, and multiform, but that needs to be evaluated by someone who knows how they were expected to interact with each other.