I have been seeing the intermittent image loading issue for a couple of months and stumbled across a solution that worked for me.
Open System Preferences.
Click Network
Click the gear in the lower left corner and choose Set Service Order.
Click the Location pull-down and choose Automatic (or drag your preferred adapter to the top of the list).
Click the OK button.
Click the Apply button.
I'm guessing that some of my requests were erronesously being routed to adapters that were not in use. Changing the service order seems to have resolved it.
Open System Preferences.
Click Network
Click the gear in the lower left corner and choose Set Service Order.
Click the Location pull-down and choose Automatic (or drag your preferred adapter to the top of the list).
Click the OK button.
Click the Apply button.
I'm guessing that some of my requests were erronesously being routed to adapters that were not in use. Changing the service order seems to have resolved it.