Import Issue and Code 2 not showed

At the beginning I would like to thank you for this very useful plugin. I hope that future maintenance will be done as well.

About my problem:
I tried to use the [Product Code 2]. It turned out that I cannot import any data. (I use the standard function of Woocommerce: Products->Import->CSV).

In one case both fields [Product Code] and [Product Code 2] were filled identically (with PC). Once [Product Code 2] was completely deleted.

Additionally, I noticed that [Product Code] is correctly shown on the product pages, but [Product Code 2] is not shown at all.

I hope this info helps you to solve the problem.

Thank you very much and best regards!