The attributes timestretch setting applies to when you set the timestretch setting on flex playback to “auto”.
This is so you can use sound locks with different timestretch settings on the same track.
Have you been intermingling with pickup machines?
Pickup machines always have timestrech active, so if you load and use one that track’s recorder buffer attributes will have it turned on. This can be overridden if loading that same recorder buffer to another flex track, and disabling timestretch in the flex setup, but just for that track…