If the Yamaha is in Straight mode and the disc bluray/UHD is an Atmos or Dts:X then Straight will use all the speakers configured. In Straight mode with only a normal Dolby or Dts it will only use 5.1 or 7.1 depending upon other factors.
To make use of the Height/Overheads speakers for normal Dolby/Dts films you need to use the up mixers. If the up mixer is DSU then Atmos discs still work normally however Dts:X will be dropped to the core Dts HDMA and then up mixed. The opposite is also true. For Neural X then Dts:X will be passed untouched, Atmos will be dropped to the core True HD and then up mixed.
The new Yamaha's xx80s models, are restricted by Dolby from up mixing Dts, so Yamaha introduced a nice Auto mode to do the correct up mixing options.
Only thing I would add about the Haunting is a friend had an American import with Dts and he believed was most disappointed compared to the European Dolby version. I would add this was an original release back in 1999 I think.