Pics disappear from my text document

My pictures disappear after being pasted into my text document. Other times the pictures remain but disappear when I export to become a PDF. What am I doing wrong??

Maybe related: (1) Can I make images available offline? — (2) I can't get a picture to stay in my document when i email it — (3) How can one paste an image embedded rather then manually breaking the link afterwards?

Another: → (4) Writer with pictures often fails

First of all, I recommend you to upgrade to the latest stable LibreOffice version. If this does not fix your problem, you have to report a bug https://bugs.freedesktop.org/enter_bug.cgi?product=LibreOffice with detailed description, problem files (pictures and text documents, result pdf files), screenshots (if available).