So… there are several reasons I use hostapd on some of my raspberry pi….. and when I do I have seen an issue. To save myself from having to look this up again I just want to note it here.
Error: Failed to start hostapd.service: Unit hostapd.service is masked
And……to fix it:
sudo systemctl unmask hostapd
sudo systemctl enable hostapd
sudo systemctl start hostapd