I am getting this issue but I am sure I don't have any issue in my application's logic because It works well until 2 - 3 times. Also, when I added time sleep, its successful publication raised until 5 times. I am getting this issue when I added eBay / store categories, so I think it can be related to performance speed of eBay publish item group. But this error is coming from inventory_item_group. I know this issue is well-know resolved issue, but it seems like still exist.
In other words, this issue appear when I create and publish offer with multi-variants continuously without any time sleep.