When we turn rotate a stair 180°, the geometry values become negative and the stair is drawled flat:
…or drawn not at all.
I experienced the same bug.
Hi @simon12, @Eugen thanks for warning about this bug. We have fixed it in the VisualARQ 2.13.2 version we are going to publish one of these days.
You can download our latest internal version here: http://visualarq.s3.amazonaws.com/download/visualarq-2.13.2.17620-rhino7-setup-snapshot.msi