Language Toggle Block is not showing

I have journal that has defined content in three languages (Српски, Serbian, and English), and locally I have almost finished translations on my testing site (OJS 3.0.0), and tested it with changing default website language, but when I check Language Toggle Block Plugin to Enable, it doesn’t show. No errors or any thing. Also Other block plugins are missing except “Make a Submission” Block.

For some reason if block’s are enabled in plugin page they don’t display on site, but if I disable all blocks so that they are in right side Appearance -> Sidebar management (Unselected) and from them pull them in left side (Sidebar) and then hit Save they are showing on site and working.