European stopover pricing issue

I apologize if there is a precise answer posted but I've searched a bunch and read most of relevant the stickys. I have purchased many TATL BE award tix in the past 10 years including open jaws & stopovers and I am well acquainted with the steps to achieve such tix. I am trying to piece together an itin for my daughter in coach and have encountered a stopover issue.

I've priced out IAH-ATL-BRU//AMS-DTW-IAH at 77,500. This makes sense because DTW-IAH is medium which forces the AMS-IAH return routing to medium.

I tried to add a LYS-AMS segment Both delta.com and EF show it as available as either AF or KL at low (25K). First I tried to add this segment with a stopover of less than 24 hours, which by int'l rules should not even count as a stopover. That didn't work, because I suspect that the medium DTW-IAH segment forces the LYS-AMS segment to medium which is not allowed on partners.

Next I tried the day before which I think would make it a true stopover. As before both delta.com & EF show low 25K availability. This does not work either. In both cases delta.com prices it at 102,500, i.e. it adds 25K for this one-way LYS-AMS segment.

Is this a valid stopover & should the trip still not price out at 77.5K? If so, do I presume correctly that I must call (until I get an agent to price it correctly)?

Thank you in advance for any ideas.