"Extensions" not appearing under Audio menu - Nuendo 11 w/ SL Pro 8

When I first upgraded from Nuendo 10 to 11, SpectraLayers One appeared under extensions in the audio menu. I upgraded to SpectrLayers Pro 8 (without my cross grade from Audition because Steinberg hasn’t responded to my submission since I submitted the request when SL Pro 7 came out, but Steinberg’s shitty customer service is another matter).
Anyway, I bought SL Pro 8 because a client was having trouble getting stems from the composer of his instrumental. I tried splitting the stems in standalone but they didn’t sound right so we scrapped that idea. Now, for the first time since then, I have need to try to use it to split a track into stems again but I wanna open it in Nuendo11 and it’s not showing up. In fact, there is no extensions option at all under audio. I have the track selected as well as the channel and even tried only selecting the channel but nothing works. No extensions option. What is going on here?