your cap is a little long, so I'm just going to do a little guesswork about what might be wrong, if you want to meet in chat, either i or someone else might be able to provide specific suggestions to try out.
1-when you switch to "hurt" animation, make sure to do "play animation" afterward. it sounds like "standing still" might be a 1 frame animation(?) that isn't playing, and so animation is stopped. Also you should have an event that when the animation is done playing to set the animation back to standing still.
[INVERTED]EnemySpawnBox - Is On Screen
----System - Every 5 Seconds -
-----------EnemySpawnBox - Spawn Object - Enemy