Printoid v5.18 has introduced a regression for those who have performed the update from an older version than the v5.17.
In fact, your custom commands wont show and your unable to add new one.
This issue does not occurs for those who have updated to the v5.18 from the v5.17. If you are in this case, please ignore this update.
I’m so sorry for the inconvenience,
Anthony
Printoid for OctoPrint 