Images added via "Add Media" on WordPress do not show, text is shown in pop-up only

Dear all,

I have a problem with creating a pop-up.

I want to add some 4-5 image with some text between them. I use the "Add Media" menu in WordPress. The images and text are shown in the editor, I do the alignments there.

However, when click on "Preview", the content shown is only the text, for the rest of the images there are some "/image tille" shown where the image is supposed to be.

Could you please help?

Thanks in advance for your help!