Live Links and formatting disappear

We formatted signatures for our company that include live social media links. They work great... unless an attachment is added to the email.

We've tested this. The moment you add any sort of an attachment (usually PDF in our case) all three live social media links lose their hyperlinks and end up formatting themselves into a straight vertical line. No other part of the signature is affected, and this does not happen if no attachment is added.

Please help! Why is it doing this and how do I stop it?