Has anyone experienced deploying but not appearing in the Extension Activation?

If your extension does not appear in the list of available extensions for your site, the most common explanation is that you have a version mismatch. If your extension's manifest you can set a 'target' version which indicates what versions it is applicable to. In some cases you may have been too exact (eg "19.2.1" and your site is running 19.2.2), specified a version in the past or not used symbols like ">=19.2" which indicate that it can be used on sites running 19.2 or newer

thanks! will check that