The preview of GH and all rhino geometry disappears from view in all viewports when the patch surface command is connected to surface evaluation. Not really sure what’s wrong though. The preview restores instantly upon removing or deactivating the patch command. Pictures and script attached.
Can you upload a simpler version of the file which doesn’t use the TTToolbox and LunchBox components? You can probably internalise all data just around the Evaluate component.
If that solves the problem, then I guess we’ll have to look deeper, but just in case it doesn’t it’s a simpler case to investigate.
I’ve had a similar problem, geometry disappearing from the perspective viewport. By disabling parts of the network I was left with the Eval Surface node. Disabling it, the surface appears, when I enable the node it disappears. A workaround isn’t difficult. Just mentioning it to help someone else solve this problem.
something similar was happening also to me in the last days (using Rhino_7 + GH)
non-selected GH components had a perfect preview (red colour)
selecting GH component made their own preview completely disappear (instead of becoming green)