UWP - No certificate found with the supplied thumbprint

Question

I have a UWP app I work on from two difference devices. After the latest Visual Studio 2019 update I began receiving this error:

No certificate found with the supplied thumbprint: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

The app previously had the temporary key Visual Studio used to auto generate that it no longer does. I generated a new key file from the instructions at this link https://docs.microsoft.com/en-us/windows/msix/package/create-certificate-package-signing and that worked on my desktop. I was able to select the certificate in the package manifest, update the "PackageCertificateThumbprint" in the csproj file and then both build and create the sideload package.

Now, switch to my laptop. I get the above errors again even though I've brought the cert I created over to that machine. The package GUI tells me that there isn't a valid cert to use. I've tried adding that cert to the local machine to no avail.

1. What am I missing that I should be doing?
2. My goal is to be able to develop on two different workstations without having to do a dance of creating a new cert everytime I switch one or have to update the csproj file every time I switch from one to the other.

This is a personal project, it's not to the point of going to the store but I do need to dev on two boxes and create side load packages for a set of testers.