What is happening to me makes no sense, especially since I've wanted this feature for a very long time in a controlled manner.
Sometimes (and I can't reproduce when) some of my columns on my Tablix Tables (not Matrix) grow in WIDTH.
For the years I have used SSRS many people including me have wanted a way to AutoGrow columns in Width but the answer has always been that they cannot and that the CanGrow property is vertical growth.
However, some of my columns are sometimes changing in WIDTH and I can't for the life of me figure it out. It is especially annoying because unfortunately the width of the report does not compensate so the right side of the report is chopped off by the total expansion size of any fields that changed in WIDTH.
Any ideas?