ArcherDougherty

Try this new code. If it doesn't work, please share link to page where you use image, we can check easier
.sqs-image-content a { opacity:1; transition:ease-in-out 300ms; &:hover { opacity:0.6; } }  

Cache would be my first guess, that's the major difference in using an incognito window. You can try clearing your browser cache to see if that makes a difference.

This needs a couple more angle brackets:
<p id="link"></p> <span id="link"></span> and you may want to use span instead as it doesn't have a line-height associated with it.