A missing favicon can have several causes, and repeatedly regenerating the image rarely identifies the problem. Work from the actual file toward the place where you expect to see it.
Can you open the image directly?
Copy the icon URL from your page source and open it in a new tab. Confirm that you see the expected image. A 200 response alone is not enough: some sites return their home-page HTML for every missing path. Check the content type and the response body if the URL does not display an image.
Does the page declare the right path?
Inspect the HTML head, not only a template in your editor. Confirm that rel="icon" points to the correct file. A leading slash means the domain root, which can be wrong for a site installed in a subdirectory. Check for duplicate declarations from themes, plugins, or framework metadata.
Are you seeing an old cache?
Test a private browser window. Clear the affected site’s cache and any relevant CDN cache if the old image persists. Different browsers cache favicons differently, so verify with another browser when necessary. Avoid changing the production URL repeatedly as your only troubleshooting method.
Is the design effectively invisible?
A white icon on a transparent background can disappear on a light tab. A complicated image can look like an indistinct dot at 16 px. Use the actual-size and light/dark previews to distinguish a rendering problem from a design problem.
Is the problem only in Google Search?
Google’s favicon selection is separate from your browser’s. Its guidance requires a square icon, a stable URL, and crawl access to the home page and image. It recommends a resolution above 48 px. Authentication, robots restrictions, or an unsuitable image can get in the way. A correct setup does not guarantee that an icon will be shown or immediately refreshed.
If the website itself is correct, allow time for recrawling instead of continually replacing working files. Search Console can help you inspect how Google accesses your website.
Reference: Google Search favicon requirements.