This is a very odd problem indeed. I can't think of anything off-hand that would immediately explain all of your apparent symptoms. But let's start with what we know. The TGD you posted is broken, as others have said. Even though you can see nodes in the Node List views on the left, the Node Network view bottom-right shows nothing and rendering the scene shows nothing as well (even if you change it from 0 detail, which is how it loaded here). I suspect you may not be seeing this same issue because the decimal separator in the entire file is a comma , instead of a period . Now what's odd about that is we have a lot of users in Germany and other places where the comma is used as a decimal separator and I've never seen this issue, so I'm not sure what that's about.
That being said, if the TGD you posted loads *and renders* correctly for you, it suggests your system is handling the decimal separator correctly, even though it's not the "standard" environment for TG3. Once I change the decimal separator to use period instead of comma, that scene renders just fine on my system. The question is whether it renders correctly for you. Is this just an issue you see *in the viewport*, or is it a render issue too? In which case show us what the rendered view looks like as that will be helpful. If it renders OK and you just see this issue in the 3D Preview window, then I would suspect it may be graphics driver related, which could explain why it just started a few days ago and worked before (assuming you upgraded your drivers recently).
- Oshyan