I know you're well versed on the "ins and outs" of these awards, MEL-Traveller, but I beg to differ. I've seen this point debated in this thread previously. I know some agents will run the line that it's a stopover but others don't. Having completed several OW J award trips and used land legs or cash flight fares extensively as part of them, my personal experience is that the stopover city is the last one arrived at on a OW flight and the city you depart from after the following land leg counts as one sector (transit) but not as a separate stopover.
I have exactly that scenario in a booking I have just completed for next year with 5 stops in JNB, LHR, KEF, (BGO+TOS+OSL+ARN+CPH) and (NCE+PMI). If a stopover was counted for each city where the OWA was re-commenced after a land leg then my itinerary would also count stops in CPH and PMI - taking my total to 7, which is clearly not the case.