Yeap! Same problem here. 2020/05/21.
But I was not able to connect HTTP port 80 even before running SQLMap --os-shell command. This Vaccine machine’s connectivity sucks, really. I found another forum’s threads were people is complaining about it too.
I don’t know if this connectivity problem is directly linked to SQLMap command, but it is possible as well. HTB support should give a look on it.