Magento – How to upload new product images after Adobe Flash Player EOL

Hook into a http sniffer. It looks like a php error, therefore the flash uploader can't parse the response message. Therefore nothing happens and the uploader doesn't call the javascript functions to add the row to the table, etc.

You shouldn't have left out <!-- Some code here-->. I'd like to see the <models> part inside <global>. I expect the error to be there. Try to change <class>Nextgeni_MostLove/observer</class> to <class>Nextgeni_MostLove_Model_Observer</class> or whatever the class of your observer is.

Another potential error: the <events> part should be inside <global>, <frontend> (not in your case) or <adminhtml>.