I recently completed Take it Back! with Star Paladin Cross, and now I can't seem to find her. I didn't use the wait command or anything, I just ventured into the Purifier as I usually would. The big kicker here is that I gave her a Power Helmet, so now she would appear to be like any other Brotherhood soldier and I can't seem to find her in the Laboratory where I first enlisted her. So, any tips on where I can find her at certain points during the day? Would she be in a different place now that Broken Steel has begun?

Try traveling back to the Purifier. OR
Travel to Pointlookout (if you have the add-on) and that automatically sends all followers back to their original point.

Worked like a charm, thanks!