Processing on NixOS: "core does not run on this architecture: linux-amd64"

Hello! I’m just starting out with Processing. I am using Processing 4 v1293, which is what’s packaged for NixOS. My code runs fine, however in the console at runtime I get this message:

core does not run on this architecture: linux-amd64

Additionally, I am unable to export to 64bit Intel Linux, with a similar error:

The application will not be exported for Linux (Intel 64-bit) because core does not support linux-amd64.

I haven’t been able to find any mentions of this error online, and I’m not familiar with Java. I can run the included Java application OK (at least I can display the --help menu), and I can run Processing code properly, I just can’t export it! Could someone point me in the right direction for troubleshooting?