Stock Keyboard disappears when typing...

Fixed! Try this.

Goto your phone settings -> Apps
Change from “Downloaded” tab to “All” tab.
Click on “Android keyboard (ASOP) and click on “Clear Data”.
Click on “Dictionary Provider” and click on “Clear Data”... you are welcome !

I know this is old but I've been having this issue for months on my Galaxy S5 I'm too broke to buy a new phone right now. My keyboard kept disappearing and videos kept pausing. A bunch of other apps were glitching out too. Ive been looking everywhere trying to find a fix for a while now and this finally did it. I think it was the "Dictionary" that did it. I cleared the cache and havent had any problems since. Made an account here just to thank you.