My last bedroom has three outlets, and are all showing "OPEN GROUND" from my tester. The third one is adjacent to the other bedroom, and that outlet is also showing "OPEN GROUND". The others in that room are fine.
My home was built around 1980, and I have never done any electrical work on those outlets. The way that I found out was because my son bought a surge protector for his gaming stuff, and it was showing "NO GROUND". So I plugged in my tester, and it read "OPEN GROUND". I have lived there about 16 years, and have never noticed a problem. I have checked all outlets, and all ground wires are twisted and connected.
Could the break be where the two rooms meet? Any ideas? My master bedroom is closest to outdoor breaker, and then it is the room in question.