Problem is this:
src="//www.gravatar.com/avatar/bd5ba0f14becd1bf0cfc950c6a7f13ae?s=80&d=//osticketawesome.com/avatar.png"

i think it sould look like this:
src="www.gravatar.com/avatar/bd5ba0f14becd1bf0cfc950c6a7f13ae?s=80&d=identicon"

Quick fix:
File: class.avatar.php
Edit line 244

$url .= "?s=$size&d=identicon";

@lafr Thats what it supposed look like. Did you read this post?  https://osticketawesome.com/forums/topic/avatars/

Hi @lafr,

I originally added my "grey man" to replace an (in my opinion) unattractive kangaroo avatar that was used by osTicket core for a user with no avatar assigned.

I failed to realize that this broke the new Gravatar options, so thank you for bringing this to my attention and also for taking the time to offer a solution.

I will have to review why I did this in the first place and I will possibly take your advice and revert back to how osTicket core handles this in a future osTicket Awesome update.