Animation not playing in ue4, why? (Blender)

Hello,

I’m here with another newbie question, see screenshots for clarification.

When I import a .fbx containing an armature and mesh it sometimes works and sometimes it doesn’t. What are the minimum requirements for importing a .fbx?

The first two images display the first exported object that shows no animations. The third image shows an object correctly exported and working within ue4 (same settings).

Thank you for your time in advance.

Greetings,