'Chrome Extension View Optional Permission Warnings Locally

I want to add optional permissions to my extension and would like to test the warning messages (locally) prior to publishing.

I followed this article, and created the packed .crx file.

However when I upload it (via drag and drop), I get:

This extension is not listed in the Chrome Web Store and may have been added without your knowledge. Learn More

...but, my extension IS listed in the Chrome Webstore.

Am I missing something, or did Chrome permanently disable .crx uploads?

Seems like there is no solution to this online.

Is it possible that my "updated" manifest is causing this issue as it is now using v3 whereas the published extension is v2?

Sources

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