Not sure if this the right place to post this question.
I added a package size and ticked "Use this package to calculate rates at checkout". Now I can't seem to untick this option. How do I untick this box?
The tick box is grey.
I suspect this is because the checkout requires a package to be selected. If none of your other packages have this option ticked, then the system won't allow you to remove the only package it uses to calculate rates. If you tick this option for another package, does this allow you to disable this option for your test package?