case-sensitive
When sigil create the original CSS, it's called style001
When it creates a new one, it's called Style0001 (note the S instead of s)
Of course, when I edited my section link , I just added a 0, and it works fine in Sigil. But ADE seems to be more case-sensitive than Sigil.
There is something weird in Sigil to maybe change in a future release (the first with s and next ones with S is strange to me)
Thank you Jellby for you appreciated help and time
Cheers,
GE