I have tried exporting the entire audio of my project to a WAV file to edit in audacity via the audio only option in render. When the audio is imported back into the project it is shorter than the original by a small amount. This also occurs if the audio is exported then just re-imported with no editing in an external editor. This also happens with different projects using clips from various sources.

I have looked at this in more detail. The imported audio appears to be in sync with the orig audio, however the last 1-2s of audio looks like it has been lost during the export import process. As a work around, I have added a 5s noise clip to the end of the project from the add clip menu before the export and then removed this clip and its audio from the project after re-importing the audio.