Whether it's for role-play or not, what do you seem to have the most trouble with? For me, it's naming. Yeah I have trouble with plot development and world-building quite a bit, but even after I manage to get through that, I find myself stuck yet again because I have no idea what to name the heroes, villians, places, everything. I feel like this bothers me a bit too much.
I find a lot of myself in this post. I recently wrote a timeline of sorts dictating the key story points of how the last few World of Warcraft expansions could have gone that would have made the world feel more alive. That’s… okay. It included a lot of variables from old and present Warcraft lore. It was fun to do. But it is so much easier than fleshing out characters, establishing relationships between existing characters, choosing the right moment to expose key character traits (strengths or weaknesses) and so forth. Actually I guess I did two WoW timelines, one based on a more specific writing prompt about the blood elf leader Lor’themar Theron as Warchief during Legion. It was a hit relaxing, too, even though I’d never serious considered the possibility before.For me it's probably maintaining interest and the writing itself. I love coming up with new ideas and they have a habit of taking over brainspace fast and supplanting existing stories I'm working on. There are some stories I always come back to though.
As for the writing, it might sound odd but I love coming up with stories more than actually writing them. Writing is often a pain in the ass since it takes a lot of concentration and focus which I simply don't have.