My TV supports 480i, 60 Hz, 480p, 60 Hz, 576i, 50 Hz, 576p, 50 Hz, 720p, 50, 60 Hz, 1080i, 50, 60 Hz, 1080p, 24, 50, 60 Hz, 1080p, 24, 25, 30 Hz and the HDR allows me to switch between 576i, 576p, 720p, 1080i and original.
It's still switching to 1080i all the time!
I had another look last night and noticed that both SD and HD were set to 1080i. Then set SD to original and HD was still 1080i. I noticed that I could set this to original as well (which is still 1080i), so I now have both SD and HD set to original. I wonder if this might make the original setting stick...