[DNSB]

I suspect that Sigil is not the best tool for locating and correcting what appear to be OCR errors.

I also tested your complaint by looking for single digit chapter number which occurs in chapters 1 to 9. I then changed the search to look for double digit chapter numbers by modifying the search term using regex. I tested ~15 epubs and no issues.

Chapter [0-9]" found chapters 1 to 9, changing the search term to Chapter [0-9][0-9]" found chapters 10 to the last chapter in the book. I then switched to a normal search for a single word. Count showed multiple results and the search stepped though all the files that had the search term.

Using a normal search, I found the same results, changing the search term effectively hit the restart search button.

I could not duplicate your search not searching the entire document after changing the search term issue. Oddly, unchecking the wrap box didn't stop the search at the last file either in most cases.

This is using a compile of the latest Sigil code from the repository but I went back through the Pull Requests and didn't find anything that I could see as causing the effect you are seeing.