I have a strange black square when running my VR application

[nikkelei]

This is similar to an existing issue on the oculus platform. I believe its called a Mesh Stencil. The closest post mentioning this problem is at:

https://answers.unity.com/questions/1804122/i-have-a-strange-black-square-when-running-my-vr-g.html

However the issue seems to exist on the Focus 3 as well. The strange thing is that it will only present itself occationally. Sometimes it is there - sometimes it is not. I assume it is a Unity thing, but does anybody know if there is a fix ?

On the Oculus this issue can be resolved by turning off FOV stencil via its debugging tool (see attached image)

Du you know if there a similar function for the Focus 3 ?