Stuck at Opening GDS file

[mtyt]

Hey guys, thanks a lot for this awesome piece of software. Many of my colleagues have been using this to make great artwork.

Now, I have a problem which may be completely my own fault. I generated a GDS file from Python, with code similar to gdspy (https://github.com/heitzmann/gdspy)

I made the process file and try to run GDS3D, but it gets stuck in the command line at 'Opening GDS file ...'. Nothing shows up.
This is on Windows. I tried the example included in the downloaded package and that one does work. I also tried the example gds with my own process file and that works too. So I think it's an issue with my GDS file. Now, I've been able to open the GDS file in KLayout. So there's something in there, but maybe the file is corrupt or something, I just don't know what it could be.
I also noted that the Windows terminal in which I run the command is using a lot of CPU (even if nothing shows up).

Any idea what the problem may be?

Thanks!

Maarten