Do you have the DYNAMIC flag set on those lights in WED?
Yup ... DYNAMIC flag is set on all lights ...
And if I delete some of the "working" lights, the other ones show up again ... so it seems to definitely be the issue with only 8 dynamic lights being active.
I've put level blocks around the MDLs (in essence "encasing" them), just in case the fact that the sewer-mdls are only one sided, but that did not improve anything ...
Cheers,
Andreas