First of it's unlikely that all of your backups are corrupted. Do you have more than one?
For clients I have 3 plus the original one stored locally if they are a work in progress. I'm afraid one copy of a project is not really a safe way of storing data. But if so there still might be something that works.
My question is why do some Bun / CWB files go bad in the first place?
I understand the CWP file system and it seems straight forward.
The CWP file contains the project MIDI and configuration data, the audio folder contains the wave files. A wise user will always use "Per Project" audio folders to keep things in one place.
I just tried this, new project, 2 midi tracks, 1 audio and I saved as a CWP first and checked the "copy all audio with project" box. The audio is in the folder.
I then saved as a CWB file to a new location and all that is there is the CWB icon, the option to copy all audio is grayed out when saving as a bundle.
So this is scary to me,, this means the audio must now be hidden from all but Sonar!!. With a CWP file audio folder, any software can still retrieve and use the audio. It is not encrypted.
I noticed both files where the same size to the Kb. 49.3, so bundle files do not compress the audio, they just hid it. So this leads me to beleieve the audio is still in there and possibly in original condition.
So it's a Sonar bug that either encrypted it badly, or the new version sucks at reading the file.
Possible issues- You are using a different sample rate?
Plug in's and version are changed from 32 to 64 bit ?
I would try and re create the system you saved the files on.