There are some reasons for this bug I think, and Blogger itself has nothing to do with it. See the fixes below that might help you solved this elementary problem.
- First, why not try to reload your blogger.com page and try reuploading the image and put it inside your blog post.
- Second fast fix, if the first trial ended up with nothing, why not try to close your web browser, and then try opening blogger again. Reupload the image and see what happens.
- Quick fix number 3 is, why not try checking your internet connection? Maybe, you have a prolonged internet connection as of the moment when you are trying to upload the image.
- Another is, why not try clearing your browsing data.
- Try opening blogger.com in another web browser like Google Chrome, Mozilla Firefox, IE, Safari, etc.
But if you cannot wait, you can try uploading your image in another free image hosting site. How?
1. Visit imgur.com.
2. Click "Choose Photo/Video."
3. Find the image that you want to upload. Select it, and press Open.
4. When your image is already inside Imgur.com, right-click the image > then press Copy image address.
5. Back to Blogger. Click the Insert Image icon again.
6. In the "Add images," click the "From a URL" tab. Then paste the link that you copied in Step 4. Wait for the image to load first. When you can see it already, click the Add selected button.
Note: If the image directly above this note is gone, then maybe it was taken down or removed by imgur.com. The image was uploaded last September 1, 2020, same day, that this post was written. But if you can still see the image, then, Imgur.com is an excellent long-term free image hosting site that you can rely on to upload and host your image.