Kindle iOS Flash Cards

I am using Scrivener 2.7.1(26120) for Mac

I am compiling my book of Kindle and using the latest KindleGen_Mac_i386v2_9/kindlegen

I have built my document using non fiction template. I generate mobi file and open with iOS kindle app.

When I select flash cards from menu the kindle app dies.

All my other kindle books work fine with flash card. Only the file I have generated from scrivener kills it.

Is there some option in scrivener I have to choose to make this work?

Can I ask if anyone has written an ebook in Scrivener on the Mac, generated a mobi file using Kindlegen, loaded their file into iOS Kindle on the iPad and got the Flashcards option working?

All the books I have bought from Kindle work with Flashcard option. I can not see anything in the literate you have to do to make this work.

My Scrivener generated doc crashes Kindle every time I select Flashcards.

We now have an answer from Amazon. The mobi file format is not the kindle format. It is a transition format that Amazon accept as input for Kindle publishing. They then covert the mobi into their propriety Kindle format. Flash cards and various other features do not work with mobi files. They only work after Amazon has converted the file.