If you paste an image into a news feed post and try to submit it you may get a red error bar saying “Your post cannot be empty” – in this instance, hit Enter after the image and type something inocuous like a full stop and then post it – it will now go through. This has been raised as a bug with the software supplier.
Also if you click Post immediately after pasting or uploading an image this too can result in the image not being uploaded/displayed. You can edit your post to add the image again and pause a few seconds before submitting the update. This too has been raised as a bug.