Recorded Audacity File Is Far Shorter Than It Should Be

I recently recorded a very long clip - roughly 6hrs and 45 minutes - with stereo audio and settings at 96000hz and WAV 32 bit float PCM. A file-size calculator tells me that these settings should result in a file of 2700MB per hour, or roughly 18GB for a 6hr 45 minute recording.

The exported audio clip is 18GB, but only 30 minutes long - the first 30 minutes. I exported a section of the audio using the “Export selected audio” feature, and am having the same issue. The section was 1.5hrs long, and using the same ratio given by the file size calculator above, it should be around 4GB for a 90 minute file at the above settings - which it is. However, the file is only 90 seconds long.

And of course, the window that Audacity was open in has magically vanished (project file not saved), and the temp files only contain audio from the first 30 minutes or so. Whilst the audacity window was open, i could freely scrub through the whole 6 or so hours of recording.

My question is - is it possible for me to recover either of these files to be played at full length? Is there just an indexing error in the file information, or is the data permanently lost? I’m hoping that the audio is still there, as the files are the size they should be for such a length of audio. As the file is 4GB and i live in Australia, I can’t easily upload it, and i fear that if i open it in audacity and re-render it then the new file will definitely not contain any of the un-listenable data i’m looking for. If anyone thinks they could help if i upload the file, please let me know.

Can anyone help me with this?

The “Microsoft PCM WAV” format has a maximum size of 4 GB (https://en.wikipedia.org/wiki/WAV#Limitations)

If you had the original (or backup copy) Audacity project, you could have exported in a format that supports longer recordings, such as FLAC, OGG or MP3.

Unfortunately I think that the over-size WAV file may be unrepairable, but you could try “Import Raw”. https://manual.audacityteam.org/man/file_menu_import.html#raw_data

Actually I have accidently done this myself and I was able to use raw import to recover the file. RF64 format is a good way to save in a wav equivalent lossless way provided you have the disk space. But if you can only find 4Gbytes of data I’m afraid the rest of it wasn’t saved.