Retail Barcode Labels

I am using this app to create and print labels for products we sell in our shop. It was working fine so far and was really easy and with just few steps I was able to print barcodes. We use Demo LabelWriter 450. I didn't need to use the app for a few weeks but yesterday I had to print few barcodes and it is not working fine anymore.
It prints only parts of the information on the label. I've been trying different settings, followed the instructions and recommendations from the app help page, noting seems to work.
Could you please give me any idea how to deal with this case?

Thank you
Mira