We went through in each direction 2 weeks back & experienced this mid-culvert pause when heading east (up). I did what most of us would - checked the prop (my wife was at the helm, as she's only just over 5') to prove no issues there. I said to her "I bet we'll find a boat just come out of lock 6". Sure enough, we then started forward again to find one outside waiting to replace us. I suspect that getting washed back when 6 empties has more effect than lock 7, as we didn't have anyone behind us ascending Hanbury.
It wasn't our only grounding. Black Prince boats had left a one-boat wide channel at Stoke Wharf. Fine, but when we tried to go through at 5 one evening, we "ceased to proceed". We were grateful to various residents on boats for helping to move parked boats so we could get closer to the central channel. In fairness to BP, we arrived home at the end of the week to a BW email warning us of low levels owing to vandalism. We got to Stoke Pound at 7.20 (this was before the clocks went forward), but my wife had earned her steak at the Queen's Head. [Other pubs are available.]