Hello,
All methods and features of phpdocx are fully tested and working with all MS Word versions and other DOCX editors. If the new image is not being displayed when doing the replacement, then maybe PHP can't download the remote image (HTTPs connection issue or missing streamMode that is required to get remote images with replacePlaceholderImage and addImage as detailed on our previous reply or any other external issue).
If you send to contact[at]phpdocx.com the most simple DOCX template and code you are running (using phpdocx standalone without using databases, web services, frameworks, CMS...), this is the code you are using to load the template and replace the image with the new image URL you want to add, we'll check it.
Also please note that MS Word 2021 support was added in phpdocx 12 (https://www.phpdocx.com/news/post/phpdocx-v12-release-notes/223). If you are using a previous version of phpdocx, we recommend you upgrade your license to the latest version to get full support with all MS Word versions.
Regards.