I found this with the SL11.070 Update and in SL12. GPU or CPU selection does not make a difference.
My original Audio is 24.764 Sec. long
Using UNMIX Components the target layers are 25.374 Sec. long
UNsing “Publikumsgeräusche entmischen” it blows up the length to 27.527 Sec.
Unmixing Song is OKAY. Layers have same length as orig. file.
Soundtrack-module is okay. Same length
Multi-Channel-Modul adds just a few frames (24.790)
Unmixing Lead/Back-Voc-Modul sets the length to 26.796 Sec
Well, I tried unmix crowd noise and, indeed, the length of the file increases.
This is utterly screwed up, I guess.
Of course, using the precious version 12.0.0 Build 421.
I haven’t seen a worse product release for years.
Has there been any testing at all before release?
If this would have been some kind of food, the department of health would have ordered an immediate recall.