Sometimes when a receipt printer gets moved and the USB port is changed, Windows will rename the printer and Workflows will lose track of it.

Go to Start - Settings - Devices - Printers and see if the receipt printer is listed.

It may be listed more than once, one of them will probably say Offline under the name.

Click on the receipt printer listing that is not Offline, click manage and then click print test page.

If that works, then note the name of the receipt printer (it may contain the words copy 1 or copy 2, etc.), this is the ‘new’ receipt printer name.

Go to Workflows, from the menu at the top select Preferences, Peripherals, and Receipt Printer.

Click the drop down box next to Receipt Printer and select the 'new' receipt printer name.

Test it and see if it prints normally in Workflows.