Please make sure that you’re not uploading overly large images, as the upload may take some time.
Additionally, could you please clarify what you mean by “failed” in this case? By default, the Save Changes button is not available until all selected images have been uploaded. However, if an image has an incorrect resolution or a similar issue, there should be a notice at the top of the page, while the remaining images should continue uploading as usual.
If this is not the behavior you’re experiencing, please provide more details about what exactly is happening. You can also share the images you’re trying to upload so we can test them locally.