AI upmixing estimates a surround mix from stereo; it cannot guarantee recovery of the original surround channels or Dolby Atmos object positions. A stereo mix combines information from multiple sources, and that process loses spatial detail. Use the stereo to surround upmixer to create channel stems, then listen for bleed or artifacts and adjust the levels in Studio. If you have the original multichannel recordings or Atmos master, use those for a faithful reconstruction.