andreurivero has told the true ! and this is a bug.
I try to explain:
in old model (x1, sd1 ecc) the single registration use only "link" mode to style, when you recall single registration it load the style that have memorized, and than apply change like volume or sound, nothing more. then in future if for example you edit intro, the old single registration recall this style than play the new intro (of course using volume and sound you save it )
in audya is different, because tha style is saved into the singleregistration file,
you don't need to have 2 audya for test.
simple create new styles, or modify an original and save into new with your name.. then save single registration using this styles, and if you want change sound or volume but not necessary for this test.
then. delete the style, or move into another folder.
load the single registration and like magic you can play the style you have deleted, simple because singleregistration stored into it and never lost.
the big problem is that if you want to edit this style you can't. you can only change volume or sound (in view mode) but all editing in edit style are lost
and this is a bug.

fantastic will be if when you save single registration you
can decide is save into internal or only link
because often is better to have only link

ketronaj hope you can talk with ketron about this