Trying to generate icon/splash but getting 400

I’m on Ionic 4.0.0-rc.6

$ ionic cordova resources --icon
✔ Collecting resource configuration and source images - done!
✔ Filtering out image resources that do not need regeneration - done!
✔ Uploading source images to prepare for transformations: 1 / 1 complete - done!
✖ Generating platform resources - failed!
[ERROR] Resource server responded with an error.
        This could mean the server is experiencing difficulties right now--please try again later.
        Request: POST
        Response: 400

Found out it was because my icon.png wasn’t the correct size 192x192