Try the given methods to fix the HP Printer Offline issue in Windows 10:
• To open Devices, type "devices" into the search box or ask Cortana to do so. • Select scanners & printers. • Make sure that "Let Windows manage my default printer" is unchecked. If necessary, click the box to unselect it. • Choose your printer from the drop-down menu. • Select the version of your printer that is showing an idle or online status if your printer is listed numerous times. • Press Manage. • Set as default by clicking the button.