Attached is the above photo showing in my browser, note the URL is h-t-t-p. If I copy this URL and paste it using the square gallery or paper clip function it gets converted to h-t-t-p-s. In fact try this - post a reply just typing the characters h t t p but without the spaces.
It shouldn't make a difference all https does is indicates is that the website/ webpage is secure. It is something that companies do if there taking details off people to give them more confidence. Don't know why its causing an issue.
I would imagine it there is either an issue with a bit of code on the forum or most likely it is doing to protect users as an https link is less likely to be spam or cause viruses. The only people that could answer that question tho are the coders of the website themselves.