Ok,
I can go to an existing thread and upload pics fine (https://pinside.com/pinball/forum/topic/the-em-seeking-parts-thread/page/9). Then, 5 minutes later, I started my own thread (https://pinside.com/pinball/forum/topic/my-new-webb-and-shay-backglasses-came) and proceded to load and attach the same number (6) of pics, with basically the same resolution (804 kb - 971 kb) - all .jpg files - and the images don't appear. One thing it does ask me is if I want to link the games I'm talking about - I just clicked ok (no I don't want to) - don't know if that makes any difference.
I'm using Firefox and someone suggested I upgrade to Chrome but I wanted to see what others say......