Since this seems like the central place to discuss this feature, I experienced a lot of issues with this last night.
In-ear noise canceling headphones
1) I tried streaming Sexual Alchemy via the SLR App, flipped on the "Spatial Audio" tab, and the audio was completely off sync. The video/audio kept lagging and it was unwatchable. Also, when I turned my head, nothing changed with the directional audio. I tried changing to different souce (h264, 2700p, 1920p, etc) but did not improve. Note it isn't my internet speed, I can stream via SLR App just fine.
2) I tried downloading the original MKV and the 5k h265 of Sexual Alchemy as well. I added _FB360 to the filename of the MKV. When watching the file locally via the SLR App, I had the same audio/video sync issues. And the video kept lagging (never have this issue with SLR Original videos before). Also, all the audio sounded very hollow / out of phase, or something. It didn't seem correct.
3) I tried watching Huge Flex, via the downloaded 5k h265 version. I noticed in Media Info it had 6 audio tracks so I figured it would be okay for spatial audio. I added the _FB360. When watching this, the audio was reversed. Everything that should be on the left side was heard on the right side, and vice versa.
Overall, I wasn't able to get anything to work properly, so I just ended up watching Sexual Alchemy in normal audio, via the 5k h265 mp4.
Hope this helps some. FYI: I really want this to work. I think spatial audio will be really cool. But there is definitely some troubleshooting that needs to happen. Also, question: do all the lower renditions of the SLR scenes listed above work with spatial audio as well? As in, the downloadable 4k/5k h265 mp4s with added _FB360 tags. Or is the MKV file the only file that supports spatial audio. This needs to be more clear.