Encarnacion has 637 minor league games in his career, 541 of those games coming as a Reds farm player. In those 637 games, he has exactly six sacrifice hits, and only two of those sacrifice hits came as a Reds farm player. His last sacrifice hit was in 2004 for Chattanooga; previously he also had one sacrifice in 2003 in high-A, one sacrifice in 2001 in low-A (Rangers organization), and three sacrifices in 2000 in the GCL (Rangers organization).
If the expectation is that all MLB hitters should know how to bunt, then the burden is on the organization developing those hitters to effectively teach them how to bunt and develop each hitter as an adept bunter while in the minor leagues. The fact that Encarnacion has exactly two sacrifice hits in over 850 games as a Red (majors and minors) tells me that the Reds did a lousy job teaching him how to bunt ... or possibly did nothing to teach him how to bunt.
They could have given Encarnacion some instruction to bunt during BP sessions, but frankly attempting to bunt in BP sessions and attempting to bunt off actual live pitching in a game situation are two totally different circumstances.
It's difficult to fault a player for not possessing a certain skill when that player's organization did an awful job at teaching/instructing that skill to that player.