electron-builder fails during code signing on Windows 10

I'm getting the following error message when trying to sign an electron app on windows. Any ideas what could be causing it? The app builds normally without signing.

SignTool Error: An unexpected internal error has occurred.

Error information: "Error: Store::ImportCertObject() failed." (-2146893792/0x80090020)

SignTool Error: An unexpected internal error has occurred.

This is the command I'm running

set CSC_LINK=file://C:/Users/me/certificates/cert.pfx && set CSC_KEY_PASSWORD=password && build --win

These are my package versions

"electron": "^1.6.8",
"electron-builder": "^18.2.1",
"electron-builder-squirrel-windows": "^18.6.0"