On the R&D Chassis Design screen, when opening the Frame Dimensions there are two sliders for Maximum Supported Engine Width and no slider for Maximum Supported Engine Height.
One of them is likely for the height, the text label was likely not changed.
If they both only do width, let me know!
The bottom slider always starts at zero and doesn't seem to impact anything.
I'm fairly sure it was working when I last used it. Might have been a regression. In the mean time, a work around is to use the assisted designer to set the height, then bounce back to the advance window to finish the chassis design.
I was able to fix this one, and I'll be in the next update.
Thanks again!