Updated LWJGL to v3.3.3, the Heart library to v9.1.0, the ImageIO library to v3.12.0, and the JMonkeyEngine libraries to v3.7.0-stable .
LWJGL 3.3.3 brings many improvements to Assimp. However, please note that models saved using JMonkeyEngine 3.7 are incompatible with older versions of JME.