I quit trying to use Sigil on my Apple "Pages" generated ePubs as they generate this weird behavior in Sigil.
Let me say that I've loaded some public domain ePubs in my copy of Sigil and all is fine so evidently it is the Pages generated ePub.
Here's the problem..
When I open the file every chapter opens with all this extra spacing. Here is the epub I generated from Apples own "Best Practices" Pages file:
If I click on the "Select Heading" pulldown and release SOMETIMES it will immediately reset to "normal" as shown below. Some chapters will NOT change and remain as seen above.
The files validate with "No Problems Found" - The ePubs work as expected (correctly) in at least 7 different iOS reading apps.....
Any ideas what's happening here in Sigil?