An issue has been identified in the ARES Commander 2019 SP0.2 (126.96.36.1990) version, with the selection of printer in the printing dialog: The last used printer is always used for the output, regardless of which printer has been selected inside ARES Commander.
As per above, this is a known issue, and we are working on a hot-fix.
As workaround you can set under "System Preferences-->Printers and Scanners" the default printer to "Last Printer Used". Then the plot is sent to the correct printer, if it was the last used printer. If that's not the case, you have to print once to the previous set printer until this workaround works.
See attached image: "Set_Default_Printer_to_Last_Printer_Used.png"