! ERROR (403) while using Onshape API
! {
  "message" : "Resource does not exist, or you do not have permission to access it.",
  "moreInfoUrl" : "",
  "status" : 403,
  "code" : 0
}
HINT: Check that your access rights are correct, and that the clock on your computer is set correctly

I have recently come across this issue after my company switched to enterprise onshape, so we no longer access onshape through cad.onshape.com.

I think that this may be an issue with how onshape-to-robot calls and accesses the standard content library. I've been able to show that through the onshape glassdoor portal that the API key that I am using can access the standard content library so I don't believe that it is a permissions issue on my end. I could be wrong though.

I have this issue when the tool is "adding parts". Any standard content library item triggers it, all content native to my workspace works fine.