Created a new world in single player and issue appeared immediately. Restarted game. No change. Rebooted. No change. 

Opened my world in Realms. Issue repeated there. Items in top row on right do not respond when trying to move to another space. I could use shift click to place items in a chest but when new items were placed in those spots, there were also inaccessible.  Cannot move item to those four blocks either.

Loaded Realms on MacBook Pro, also 1.14.4 and no issues.  Then uninstalled and reinstalled on Win 10 PC and issue still exists.