Here's a screenshot of what I see inside the db folder on a PC.
See how this set of files corresponds very closely to the nested db folder in your screenshot?
Comparing the typical folder structure on my PC with what you've shown in yours, it looks to me like you need to select the contents of the second db folder (minus the already_in_use.lock file) and compress those files.
If doing so still does not work, then the only thing I can conclude is that the cached files may either be corrupted by the crash, or else do not contain everything required to construct a valid CPTX file, or else the default MAC compression utility doesn't do the job the way that Captivate needs to have it formatted.