Supported printer not supported

According to the developers page, HP LaserJet M111a is supported as of HPLIP v. 3.21.10. Despite Herculean efforts on the part of the Linux Mint support forum over several days, we cannot get the printer to work. When we try, we get a message saying, ""Stopping job because the scheduler could not execute a filter". In the resulting Document Print Status, in the "Job attributes" drop-down, under "job.printer.state.reasons" it gives the value: ["cups.missing.filter.warning"]. Does this mean that this printer is not yet actually supported?