Hi,
For what it’s worth, the stepdown on your latest flight (KDFW-EDDF) is required due to airway restrictions after SPI on T180. This is not a bug, nor is it unrealistic.
The “Plan Stepclimbs” is a little bit misnamed, what it really should be called is “Plan Altitude Changes” since it enables both Stepclimbs and altitude changes due to airway/airspace restrictions.
In the future we may split this into 2 separate options, but no ETA on when that might be. For now the only workaround is to do what you have been doing and manually enter the step climbs into your route, luckily this is easier now using the “Calculate and Compare” button instead of having to generate an entire flight plan:
Best regards,