I've been using an email signature for more than a year without issue. Today I changed the email signature to add another social link. Suddenly, if I cut and paste anything into the body of my email it will make the logo disappear. Thinking it had something to do with the new signature, I deleted it and put the old signature back in. Now the same thing is happening with the old signature.

If I type in the body of the email, the logo stays where it is. It's only if I cut and paste some text above the signature, or above anything I've typed above the signature. It's bizarre. Any ideas?