Extentsions for Sharpen4Web and Watermark Pro not properly signed - Ideas?

Could you please give the following a try (if you haven't already)?

1) Go to https://exchange.adobe.com/my-exchange.html/apps/cc/sort/mostrecent
2) Search Watermark CC and click on the blue button “Remove”
3) Wait a few seconds until you get the notification that the panel is removed
4) Mac: Navigate to [yourharddisk]/Library/Application Support/Adobe/CEP/ and remove all folders with the word “watermark”
Windows: Navigate to [yourharddisk]\Program Files\Common Files\Adobe\CEP\extensions\ and remove all folders with the word “watermark”
5) Install it again by going to https://exchange.adobe.com/my-exchange.html/apps/cc/sort/mostrecent and clicking on the blue button “Install”
6) Wait a few seconds until you get the notification that the panel is installed
7) Restart Photoshop

Found here: https://pixelsucht.net/photoshop-watermark-cc-plugin-panel/forums/topic/not-properly-signed/#post-626