I have not heard of such a problem.
I would doubt it is a problem with the stair tool as if it were there would be thousands of others here saying the same thing.
I would suspect a problem with you machine or the installation of the software.
Make sure you have the latest update for Archicad.
Are your machine drivers (video in particular) up to date?
What are you machine specs and operating system?
What version of Archicad are you running?
And I don't like to ask this but do you have a legal license for Archicad - not a cracked version?
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10