Please check product configuration. It has several options controlling which threads can be specified as deal threads. In your scenario, the option "Check Thread Starter" seems to be enabled. This option is for the cases, when the thread starter is "seller" (service provider etc.) and people replying in thread are the buyers. So the product expects the feedback to be posted by the buyer first as review of the trade, and in that case the seller will be able to leave a feedback back. Please confirm, that this scenario works on your board. If you need it the other way as well (the seller to leave the first feedback) we can implement it in the upcoming release.