Puzzled

Clicking on some of the posted photos on this blog will allow you to view a larger image. Clicking on others does not, but just give you a little toolbox with an option to Save, Print, etc. I can't discern a rhyme or reason as to why which does what when.

When I originally uploaded the Mama's Boy photo below, it would not allow enlargement. So I deleted it & reloaded it without any settings changes, & now it enlarges fine. Many others have acted similarly.

As was famously said, "Any help you could give would be most, er, helpful."