I have intermittent problems exporting PDFs from Layout.
The reseller told me that the problem lay in me importing pre 2020 models into Layout.
Over writing the whole model with a 2020 version is not enough.
The only way to make everything work is to systematically go through a pre-2020 model to find which group, component, line or imported base drawing is at fault. When a model might contain thousands of elements this process can take hours. That’s just insane!.