SteamVR error 501 on launch of packaged exe

Hello, we’ve got a strange issue with our project’s executable file.
When built from UE4.21, launching our project will cause SteamVR to stop functioning with the error code 501. I cannot find anything about this code in SteamVR online, although I gather the number is generally used for failed attempts to communicate with a server. The actual error message and display look as follows:

262629-capture.jpg

Importantly, this error only occurs on one of our computers, and not for a nearly identical project in 4.16.
Both computers are running windows 10, and have the latest version of UE4 and SteamVR installed. Has anyone else experienced this issue, or have any insight into what might be going on?

Edit: The project ran successfully without crashing steamVR twice, leading me to believe that the network settings (firewall, permissions) I’d altered fixed the problem. This was not the case; the launch of the exe once more produces error 501, regardless of network settings.

This is the first time that we’ve tried to run our project in 4.21 on this computer, and blank projects in 4.21 work just fine.