The given command works fine here, so I suspect there might be a serious problem with your installation somewhere, also because I just read another thread here where @iwalker tries to help you:
So take care and backups.
In our internal documentation the variable you’re referring to is still listed as the way to check the queue before the command @iwalker quoted came along (our documentation says it was in 12.9 from March 2020). It should be safe to try (but as your installation seems to have some problem, there’s no guarantee) and here it is only about one second slower, but the commands take above 40 seconds, so that doesn’t seem significant.