Nested block visibility problem

Hi! I’m having a strange problem with nested blocks, involving having a double sided material in the file.

It comes and goes, but Ive discovered that if I have a double sided material in the file some nested blocks are not visible in rendered mode. They are fine in shaded, arctic etc.

Shaded mode:

Rendered mode: (no monitors show up)


File attached.
thanks!
NestedBlocksProblem.zip (16.7 MB)