Situation That Brought This Out
We had this happen February 27th, 2019 and when going down to the Circulation Desk, Cynthia and I both remembered this happened before, we fixed it and forgot how/why.
Turns out this issue is when the wrong printer is selected. When the transaction is closed out and it's sent to the printer, if the wrong printer is selected, Sierra hangs and outright freezes. It basically doesn't know where to send the job.
I remedied the situation by making sure the RECEIPT PRINTER was set to Local Printer, please see the screenshots below.
For the step above, you would select the EPSON 220 Printer