I confirm that the problem does exist. I have seen it myself with the same combination.
The 2300 worked perfectly with other speakers and the BL3's worked perfectly with other Beocenters such as 9300/9500's.
In the event the 2300 and the BL3's were not sold together so the problem "went away"!
My guess, at the time, was that I needed to use Mk3 Powerlink cables. I never tried them as I didn't have any.
That is still my guess.