By default, the configuration in Red Hat 8 is set so printing to a HP 4000N prints to tray 1; which is the manual feeding tray. To change this ridiculous behaviour, become root and edit the file
/usr/share/foomatic/db/source/opt/omni-tray.xml
Go to line 1266 and change the string TRAY_TRAY_1 to TRAY_TRAY_2. Done.
I already logged a bug for this when still using Red Hat 8, but it's not solved in version 9. So much for logging bugs.
Update: this doesn't always seem to work for me. Alternative: when configuring the printer, go to the driver section. As the driver, don't select a manufacturer (leave it on 'Generic') and select PostScript. It'll now print to the default tray.