Item variants: Cannot change Variant properties after stock transaction. You will have to make a new Item to do this

Hello,

For a second day now I’m puzzled by this issue. I’m trying to incorporate item variants but I keep getting same error “Cannot change Variant properties after stock transaction. You will have to make a new Item to do this.” Even if I just trying to create the most bare bones item and add variants to it, I get this message. It doesn’t matter if I am using my attributes or default ones. I tried to replicate this issue on ERPNext trial version, but there it works like a charm. Hope someone is more inclined in this than I am. Thank you.