Keep Open is greyed out

[Okani]

 The keep open option is greyed out, although there's no application using it. 

[AndrewL]

@Okani: I can see that you're in the Settings menu, which might explain why the option to keep it open is greyed out. If you open a specific application, tap the Home button, then hit the Recents button, and tap the tile above the preview window for the app, is the 'Keep open' option available for selection? 

[Koushik1]

I had the same issue, I had one more app which was kept open. Unlock and try locking this

[Midhun_gpr]

I tried .still not working bro