I think what happens is that when you create the hyper link it doesn't show up as blue because you have been to that webpage when you created the hyperlink, but readers that have not used that link have it show up as blue.
At least thats what I think happens.
I have noticed the same issue, but if I read my post on another device, it shows up as blue.
I believe the blue disappears after a reader goes to the link. If they come back later then I think it's invisible.
The alternative is to copy and paste the entire link which I know can appear messy in a thread.
For a while I was posting links with this in front of it:
"I get that queasy how in the hell will this thing ever go back together feeling.” - PT