Thanks basicX. I replied.
I have an answer to the problem. So if anybody comes across this again, here’s the solution.
It’s entirely the problem of the process we applied. Michael from AATranslator found out what it was. Since we wanted to avoid sending over 12GB of audio project data, we thought we could get away with only sending the PT session file and let AATranslator do the work, and send the transformed file back.
It did work. AATranslator converted the PT12 session into a Nuendo Track Archive. But since AATranslator could not find the audio data, it registered all audio files as 0,000s in the Track Archive. Nuendo imported this false information and even though the paths to the original audio files are all there, Nuendo has the files registered as 0,000s in the pool and never updates this information. Thus, not playing any audio. Or better, it plays the audio, but only 0,000s of it.
TL;DR Solution: If you want a proper transformation of a PT12 project, ungroup all clip groups, save the PT12 file, and make sure that all the audio data is accessible by AATranslator when converting the project. Track Archives for Nuendo save more information than AAF so it’s the better solution.