Hi Jeff, This happened to me, What you have to do is Upload the background to the background folder again which is located at core/signature I think.
I found out that the Background folder was deleted, so make the Background folder again and put the background.png back on with the permissions 0777 (x10 hosting/cPanel) or 777 <- there the same thing just different ways of it.
Go into your admin center and click Maintenance and click Reset Signatures, It should work.
If it doesn't work click Optimize Tables
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