Ok when I click on the arrow, it comes up the same as in your 1st screen shot, then i tap the open book, in the middle of the bottom row as per your 1st screenshot. what then opens for me is a drop down box asking me to add a bookmark, if I try to add a bookmark of the site I am on at the time when that opens it wont save them in the bookmark it saves them in history as history
I click on the book in this pic
Then this comes up
Look at my second picture. There you have to tap the open book.
I have no idea what I just did but i tried to take another screenshot and ipad closed down again and rebooted this time they are all there....
That 2nd picture you took wasn't coming up it was just coming up as save bookmark. no matter what I clicked on all I could get was that add bookmark or history, but when it powered off and rebooted it all came back as normal. thank you for your assistance anyway, it is appreciated...still can't work out what happened to make them disappear, but at least they are back now