Hello i made an animation recently but, it shows up in 3dmax perfectly (https://i.gyazo.com/f7ba107a50b4025f4e33e1a497907570.gif) like in there, but stays idle in model viewer in sdk, followed your tutorial, and made 1 animation succesfully before, so should be fine in theory, is it by any chance too complex animation? or i messed up somewhere,
settings i have used: (https://i.gyazo.com/50a6ed7534ea46c2d7c2a06e22c70252.png)
(https://i.gyazo.com/ec0321d6b3f334a1211c93c6ad3f885d.png)
Vertex animations are not supported with sequence animations. Only skeletal animations (movement of bones) is supported. This means that you cannot export a simulated cloth, etc, and expect it to work in Source.
The way you'd accomplish this is to skin the flag to some bones and animate the bones to have a similar effect.