Thank you very much for the report and I am very sorry about the issue!
From my experience, the issue is usually caused by walls are not 100% parallel to each other. One way to check is to set the 4 digit for measuring angle in the Dimension style, then use the Angle dimension tool to measure the angle between the 2 walls. If there is a small deviation, we will see something like 179.9999 or 0.0001 degree. If that's the case, we must manually reset each wall in the project.
Please let me know if it helps with the issue!
Technical Support Engineer