Thanks for the file which helped me to reproduce your issue. [:)]
The problem comes from the small walls you drew in some corners as shown in the following image:

As you can see, it creates some walls that may have a null length side, and a part of the program that measures the distance between an object and wall side failed for a side equal to zero.
I fixed this bug and the correction will be available in the next version.
Meanwhile, you should avoid these small walls and connect directly walls while drawing them.