I've had the same thing happen to me. Couldn't feel any break, but defintely a (slow) descent rate. (I was solo that day and the plane was empty, so cp vs.cg not really a factor to explain it, but it took agressive forward elevator to recover.) After that happened, I researched it and concluded that I had perhaps experienced a deep stall. (which is generally an aft CG related issue.) Anyways, at that high angle of attack there's that low velocity wake that trails from the wing during the stall. If the horizontal stabilizer falls within that wake, elevator inputs and feel are definitely affected, which might explain the lack of feeling a break. If the wake is strong enough, the elevator inputs can become useless and its really difficult to recover. I'm not sure that i diagnosed it correctly, or if that explains my experience or yours, but thats my 2 cents for what its worth.