After upgrading to ITMS 8.7.1, you noticed that iPXE web app was not created.
ITMS 8.7.1
Issue seems to occur on a site server without .NET 4.8
You need to make sure .NET 4.8 is installed and NBS service is present:
msiexec.exe /x "Symantec_DeploymentSolutionSBS_8_7_x64.msi"
msiexec.exe /i "Symantec_DeploymentSolutionSBS_8_7_x64.msi" /l*v sbsInstall.log skipaim=1 REBOOT=ReallySuppress