When I am trying to format all equatoins in my document using
"mathtype-format equations", some (not all) space between words and
equations will be automatically deleted!

For example, I have "... in x". After formating, the space between "in"
and "x" will be removed. Even if I type a space again, it will
disappear if I format all the equations again.

However, sometimes, spaces between a equation and other words are not
removed. I don't know the rule. But the spaces in a line with "both x
and y" are kept.

Anyone knows why this is happening? Is it because of some auto
correction fuction of word, or it is a bug of Mathtype?

(I have checked the options of word, but still have no idea).

Many thanks!