3D reshape issue

[MogTheSmilingCat]

Hi Folks, and Help! (please)

I've set up a simple building as a 3D model. All works as expected until I create a wall and then try to vary the height using 3D reshape to drag the ends vertically. They move okay, but instead of a wall with a sloping top, the top of the wall stays level but follows the height of whichever end I drag highest. I subsequently found that telling a roof I wanted gable walls results in a similar issue - the gables are square topped, level with the ridge (like parapets).

If I create a new file and try this, it works fine - leading me to suspect I've accidentally set some weird, well-hidden setting in the original file to produce this (very, very) annoying result. Can anyone tell me what??

Many thanks

Phil B

[gmm18]

Anyone have a solution to this?

..." instead of a wall with a sloping top, the top of the wall stays level but follows the height of whichever end I drag highest."

I just got this in a file. What a pain to rebuild the entire file.