[KevinH]

You could just pm a private link to DiapDealer or myself here on MR. We can then use it to track down and fix the bug without you needing to make it publicly available.

BTW, Alternatively, try using Find and Replace to a selected body tag contents with the same a single paragraph of text. If Restructuring the that works, then you know the issue is with that file's content links of some sort. But depending on the number of files, this may take a long time.

Or try find and replace and turn on the Text Mode flag and replace all (ie outside tags) with nonsense text.

Or, make a Checkpoint, then run Mend on all HTML files and see if the restructure bug still happens. If not compare it to the Checkpoint to see what changed.

Or try running epubcheck to see if it detects anything unusual about that epub that could give us a hint about what is going on.

Please do let us know what you find, as Sigil should never crash.