ISRC in AAC file

Today I just noticed that I can embed ISRC codes into mp3 files but not AAC.

I wasn’t sure if AAC supported ISRC but when I loaded the AAC files into Sonnox Codec Toolbox Manager it allowed me to fill in the ISRC codes on the AAC files.

Am I missing a preset in Wavelab for adding the ISRC codes to AAC files or does Wavelab just not support this?

No. With which “key” ISRC is associated in Sonnox Codec Toolbox Manager?

I’m not sure how I can check which key Sonnox is using but here is a screen shot of what I see in the app:
I could also PM you a tagged file to inspect if that helps.