I have added favicon files (.png, .xml, .ico, .svg) into site/templates/images/favicon/ folder. I refer to them in _after.php, <head> tag. Problem is that favicon does not show. When I go to the address of the .png icon, it shows the basic blue icon with question mark = something is wrong. But when I check .svg file, it shows correctly. Browser console and ProcessWire error log don't recognize any issues. All files have chmod 644, and all folders 755. All images added into site through ProcessWire admin are displayed correctly.
What could be the caused of this issue?