For issues you find with the Switch and Console releases, please follow this link and give as much detail as possible. This is the speediest way to get info to Pipeworks and get a hotfix in the works.
For issues you find with the Mobile 1.3 update, please follow this link and give as much detail as possible. This is the speediest way to get info to DR Studios to look at your issue. Also, some troubleshooting hints here.
Large offers more than the other sizes with advantages such as:
More Shadow Orbs and crimson hearts
More Floating island
More Demon/Crimson alters
More Jungle shrines
More underground Cabins
Larger Underworld (For wall of flesh)
Bigger oceans (For Duke fishtron)
I usually play on medium worlds, as they offer a good compromise between small and large. Large worlds do however have the most items scattered around, but they can take a long time to fully explore, and containing the Corruption/Crimson is more difficult.