Tam Nguyen and the co-founders, I have found the persistence of these missing thumbnail images/Blue Question Marks to be quit annoying and in my opinion targeted to certain site members what/who is the cause and why is little to nothing being done about it.
New Upload 3/29/25 all assigned popular tag and my profile page have thumbnail / Blue ? not of my image.
Problem corrected in twenty minutes after I posted this to my Portfolio.