Just to be clear, open G tuning is: D G D G B D. Left to right, heavy to light strings. Normal tuning is E A D G B E.
So you tuned each string individually, then went back and made sure they were all in correct pitch according to the tuner, but when you play them all at once they don't sound right? That wouldn't make too much sense. If each string is in tune according to the tuner and you have them tuned to the notes above, there is no way it wouldn't be correct. Again to clarify: Each string played individually is in tune, but all at once doesn't sound right?
I can only assume you aren't tuning the notes to the correct pitch since you mentioned it did the same thing on 2 different tuners. Also note that you are tuning DOWN on the changed pitches. E down to D, A down to G.
Check your intonation too. I don't think that would have anything to do with it since you are checking the strings open, but might as well make sure your guitar is good anyways. 12th harmonic vs 12th fret tone.
