When attempting to compile HEVD using the .SLN file (Visual Studio Project Solution file), the following error is returned:
Invalid argument <HEVD.crt> for property <TestCertificate>. HackSysExtremeVulnerableDriver C:\Program Files (x86)\Windows Kits\10\build\WindowsDriver.common.targets 1422
This is due to the .SLN file still using the HEVD.crt file rather than the HEVD.pfx file which is included.
After testing it appears this doesn't affect the .BAT files as they have already been altered to use the HEVD.pfx file, so only the .SLN file is affected. Discussions about this matter revealed that the issue can likely be fixed by altering the .SLN file to use the HEVD.pfx file and then supplying a valid password in the .SLN file so that HEVD.pfx can be opened and utilized by Visual Studio to sign the driver.