a pet hate of mine - fonts embedded in MTEXT.
your set up is correct, the style is still romans but a text modifier has crept in. People who don't understand text style often add the font information into MTEXT and mess it up for everybody else. My guess is that the font button got clicked accidentally at some stage and has added the first font in the list. If that is not the case I don't know how it has happened.
Is this happening on all drwaings or on just an isolated one. And are you sole worker on the problem drawing(s)?
There are several ways to correct this, the simplest being to explode the MTEXT. It then reverts to DTEXT but loses font information. Alternatively you can dedit each piece of text to remove the font information or correct it to ROMANS. Alternatively look in the LIST section of this forum as I think a routine was written recently.