I’ve been in touch with Pix4D support and it sounds like it is a problem on their end. I recieved the following response from support this morning:
“We have managed to reproduce the issue from our side in multiple machines. Additionally, there are more projects with the same issue and other users experience the same error. That means that it is something related to our processes, rather than your machine. I believe if you try to process the project locally you will not face any issue.
Our investigation up to this point indicates that there is an problem with downloading the results of step 2. However, our developers need some more time to better understand the issue in order to fix it.
Since I cannot provide any time estimation of the fix, I would recommend running all steps of processing locally in order to get the results faster”