Obi softbody catching on the edge of collider

[josemendez]

I tried increase thickness, but changing Thickness parameter of Obi collider is not presented in scene view. Only original collider is visible. 

Thickness only affects the way Obi particles react to the collider. The "original" collider is not modified in any way (as it's part of Unity's physics engine). Quoting the manual:
http://obi.virtualmethodstudio.com/tutor...sions.html

Note that ObiCollider's thickness parameter is independent of Unity colliders' contactOffset. You can use both to independently adjust collisions with Obi actors and with other colliders.

Add a ObiParticleRenderer component to your softbody to visually debug particles and be able to tell what might be causing this. Box corners aren't treated differently than any other collider, so unless there's something off with your setup they should pose no problem.

let me know if you need further help.