I have a customer that has a drawing with a hole callout that has a style (formerly called favorite) to apply a tolerance, and when the drawing is saved and reopened the tolerance is gone. They are using the ISO standard. I did a quick search of the forum and didn't find other cases of this, but it seems like a big enough problem that people should be concerned. It may have to do with the fact that the drawing was created before the SolidWorks switch from Favorites to Styles. The file extension for favorites changed.
If the hole callout is replaced with a dimension, all is well, the style sticks.