Elite: Dangerous PvE - Mobius

I have tried using my domain, I get the broken image symbol. It is the right size and format as far as I can tell. Initially it was too big and I got a message explaining that.
Am I using the tag right?
{img}httpblahblah{/img} (Square brackets though)
I wondered if it was the domain, tried an Imgur link and it failed completely!

My signature pics embedded is:

{img}https://i.imgur.com/blahblahblah.png{/img} with [ ]'s and it's still working.
It may be the age/background scripts of this very old forum, perhaps...