Mysterious image problem

I have a strange problem which has been going on for some months. All worked fine before, but suddenly I found when I published a new post it would come through on my IPad without the image. The caption is there and the text is there, but not the image.
If I look at the email on my phone or on my laptop, it’s there and all is well.
No one else mentioned it so I carried on as normal and subscribers seemed to be getting the images. But just recently a friend said she isn’t getting the images.
She has to copy and paste the link at the bottom of the email to go to the website to see it, which is rather a pain.
As my blog is all about my drawings, this is quite important.
I can’t understand how they show up on my phone and laptop. The posts on the website are fine. I don’t know whether other people who look at the posts on their IPads are getting the images or not.

I haven’t changed any settings.

I’ve tried adding smaller images, but it doesn’t make any difference.

This is driving me mad so I would be very grateful if anyone can work out how to put it right!

Thank you in advance.

The page I need help with: [log in to see the link]