3790123 - Why the bid decrement I configured is not enforced in a Guided Sourcing reverse auction?

I configure an English reverse auction with Improved bid amount by: Nominal Amount and Bid Decrement, but suppliers can submit revised bid with a decrement below the bid decrement without any validation errors. I expect bids below the minimum decrements to be rejected.

Reverse auction, Nominal amount, Minimum decrement, Bid decrement, Improve bid amount by, Competition term, Front buffer, Back buffer, Revised bid , KBA , BNS-ARI-GS-EVT-RUL , Guided Sourcing Event Rules , Problem