SKU not found

I’m preparing new products on my test website. I’ve started with an full import of all products, then i changed the description and pictures. Synchronising still works here. Then i exported them with the default Woocommerce option.

Now i’ve imported them with the default Woocommerce option to the actual website and i’ve installed the plugin and made the import settings exactly as the test website. However, now i get the following:

[20:01:46] Combine all data for post …
[20:01:46] Find corresponding article among previously imported for post …
[20:01:46] Duplicate post wasn’t found with unique key <anonimized>…
[20:01:46] Applying filter pmxi_article_data for
[20:01:46] SKIPPED: The option ‘Create new posts from records newly present in your file’ is disabled in your import settings.`

I’ve checked the SKU’s over and over again and they’re all exactly the same as on the test website. But somehow the plugin doesn’t find them.

Wat could be wrong?