if you look at this other thread https://h30434.www3.hp.com/t5/Printing-Errors-or-Lights-Stuck-Print-Jobs/Error-Code-11-M234DWE-Genuine-Toner-suddenly-stopped-working/td-p/9334587/page/3
it appears to be a bug introduced by a firmware upgrade released around March 4th. I have made the admins here aware of the issue and hopefully HP rectifies the situation quickly.