I'm not sure why but I've noticed that "call horse" will randomly not work at certain times, regardless of how often I press the call horse button. I've tried rebinding the key in case there was a problem with that but no such luck, it didn't work.

I think it's happened after fast traveling to remote islands, calling horse, then going back to a larger island there. That doesn't really make sense to me since I can't remember this problem on the continent, but that's just what my experience has been. Could be unrelated to the problem.

"Call Horse" sometimes doesn't work anywhere...

When this happens to me, I quicksave the game and reload it. I am able to call Roach once again after the game loads. Hope that helps you bros

Helps to me just walk away so the horse disappears from the map and after next call it usualy works fine.

Same here, reload works fine ! don't know if CDPR is aware of this little issue

Well this "little issue" makes me crazy when it works just once of fifteen attempts. I'd rather clean his ears with an arrow. I can whistle my lungs out, but he keeps licking the paving in the middle of Novigrad street instead of moving.

..

For me it looks like witcher run about same speed with the horse. So i stop call it. (Geralt didn't loose stamina in a couple first seconds, so i just tap a button and run so long as needed).

Strange, but horse in game climbing better than Geralt so i always call it in mountains.

It'll just take some time. Roach is, after all, swimming all the way across the sea from Velen ;)

Given how only one captain would take you across to Skellige, and for a cool 1000 orens, it's amazing how a single visit opens free transfers both ways.