Some of the epubs that I try to edit in Sigil end up opening with all of their files in the "Misc" folder. This is because they have no extension of .html or .xhtml, their filenames are things like html_split_000, html_split_001 etc. This is probably 1 in 10 of the ePubs I edit, so fairly frequently.
These files appear to be completely uneditable in Sigil (you cannot open in any way). However what is worse is that if you make the mistake of clicking Save on that ePub (thinking you could still safely edit the Stylesheet), Sigil will save the new directory structure it uses, but not update any internal references in those files linking stylesheets or images. So your ePub becomes horribly mangled.
The only approach I have found is to use Tweak ePub in Sigil. But then you cannot do features like merging/splitting which is one of my top reasons for using Sigil.
Are there any plans for Sigil to address these ePubs? I have no idea why they are named in this way (some editing tool or something?). It would be nice to somehow bulk select those files in Sigil and get them renamed to have a Sigil friendly extension (e.g. .xhtml), moved to the "Text" folder and keep all relative references to stylesheets, TOC etc intact. Pretty please
. Or if someone else has an alternate approach please share.