Custom Product Tabs with Wp All Import not working

I’m trying to globally add a costum tab to all products using WP all Import. I select Yes – Use Saved Tab Title & Content (but I even tried Yes – Edit Tab Title & Content without make any changes) and I use a file just referring to the product sku (but I even tried with a file with some other datas like title and description) and it’s not working.

I’ve manually added the tab to one product and it worked, can I privately send access to the website to someone in order to check it out?

Thanks in advance