Barcodes are reverting to Shopify barcodes on their own

[aksmochi]

We have had an issue lately where barcodes are changing at random. We use included barcodes on many items and have for years, but now as of this week many items that once had a 13 digit ISBN or a barcode we manually entered from the product have changed to random barcode. When we go to ring customers up the barcodes do not work anymore and when we open Shopify the barcode will be entirely different than the one printed on the sticker barcode. 

No one has reset all barcodes on accident, and that is easy to verify because we have 1000s of products and have only encounter it on maybe a few hundred. The only common thread I can think of is it seems to be products that had either shorter or longer barcodes than the Retail Barcode Label App specific 8 digit barcode. 

Has anyone else ever encountered this issue or know how to fix it?

[HardyBoy]

This appears to be exactly what I've just encountered. I was in our warehouse manually entering codes from a shipment and kept noticing products that had a previously entered code such as "210000004321" and I kept thinking to myself, I am quite sure I've never entered that. I just went to verify with a bulk edit and this is happening across dozens, if not hundreds of products. Almost every product that didn't previously have a code, with the exception of variants.

So where is this coming from? Is this some new Shopify feature/setting? If it's going to make our products get penalized on Google I'm going to be really annoyed.

[HardyBoy]

Omg... I figured it out randomly when adding a new product from our POS. We recently migrated from Accumula to their new integration called Mortar. It appears that Mortar is importing product IDs from Lightspeed as the GTIN 🤦‍

Hope this helps someone!