It measures fine for me too, but I discovered something new (to me) about it. This may have been the behavior in previous versions and I just didn't notice it.
In views in a glyph window above 6000 pts the measured width numbers begin to go outside the background panel. I did some more tests this morning and see now that while the plugin background panel isn't tied to a grid, the width number is (base aligned), even if the user has grid/steps set to 0/0. Here's a screen shot of two instances: