Starting this as a discussion in case I'm missing something (i.e. before reporting as issue). Consider this code which displays two progress bars one after the other. If you comment out the highlighted line, the second progress bar isn't displayed. Works as expected on PowerShell v5. Looks like some timing issue?

Write-Host "Testing1"
Write-Progress -Activity "Testing1" -Id 1
Start-Sleep 5
Write-Host "Clearing1"
Write-Progress -Activity "Testing1" -Completed -Id 1
Start-Sleep 5 # comment this line out and the 2nd progress bar doesn't appear
Write-Host "Testing2"
Write-Progress -Activity "Testing2" -Id 1
Start-Sleep 5
Write-Host "Clearing2"
Write-Progress -Activity "Testing2" -Completed -Id 1
Start-Sleep 5

NOTE: if you miss the completed line out, the 2nd progress bar is display without the delay. It's the action of completing it that appears to be the problem.