MAJ100X Fret Buzz even with PLEK

I have bought a white MAJ100X Sterling. I had it pleked by Thomann and perfectly setup. The frets were very uneven so I did not have to pay for the service as it was under warranty. Unfortunately, the G string buzzes horribly on almost all frets. I had a days long discussion with Thomann because of it and they double checked and said that the guitar is set up in the best way possible and they don’t know why this is happening. The G string even buzzes with a height of 2mm. The tross rod was adjusted perfectly.

It does not buzz when played open.

We tried different string gauges, different tunings – nada. The G string keeps buzzing like there is no tomorrow.

What could the issue be?