It is still present, but in a different way. When the armor stand is teleported and rotated at the same time, in some cases position does not change. I can't show how to reproduce it because it is completly random. This is how it looks like.
The report has been updated with the necessary information describing how to reproduce the bug.
Yes, those sounds are stereo. Mono work normally, but after such a big change on the official wiki should be some information about the new functionality of sounds.
Yes, this is the same bug, but here I describe what was not mentioned there. Sorry for the duplication of this bug, but due to the lack of filters for pre-releases, I couldn't find that report.