I'm a bit new to Houdini so it might be something simple.
The scene have only the "cup" (a modified Tube) and the FLIP trying to fall inside the cup.
I've unchecked the "Use Volume Based Collision Detection" on the cup, it's a static solver. Despite of that everything is on default settings.
Could the Volume Based Collision be the solution? I couldn't create an accurate collision shape with this option on.
Thank's,
Alvaro