Define equals bug? (Mathcad 14)

Try the following:

Maybe I am understanding incorrectly, but nothing after the = sign should affect the definition of "This", but it does. If I format the result by putting mW for the units on the far right of the definition it changes the value of "This" from mW to W (i.e. it multiplies the values of the definition by 1000).

In fact if I put W*A on the far right (on the defition line) it does not change the value of "This". However if I put W*mA on the far right it again multiplies the definition of "This" by 1000.

I searched in the old Collab and this section, but did not find anything.

Am I missing something here?