Thnak you Tikaram,
I tried both (regenerate and twenty seventeen). Did not work. I did some further investigations and found out that the problem only occurs on the apple platform (and not for example on android). I found I hint on internet. Save the foto’s with “paint”. This did work.
Seems that apple looks at other info in the photo than microsoft. Still strange that is everything works fine on my other blog. But anyway : this problem is solved.
Thanks again
Herman