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.
1.4 will bring many changes to the PC version. We strongly advise making plans to back up your worlds and players prior to updating your game. More details here.
Begin your search for Journey's End information here and here. Please report bugs and issues for Journey's End here.
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.
For mimics, flatten out a forest area just below the surface to get a dirt wall maybe 50 tiles or more in either directions. Fill in most voids below the surface you can. At this point, you can build an area in the middle with a water candle from a dungeon and drink a battle potion. Kill everything that comes at you. I have also found in mobile an elevated platform also helps spawns, 20-30 blocks above surface. In that case use 2 water candles (at surface and platform). Eventually, you can farm temple traps and wire an arena for events with this. Edit: mimics can spawn almost anywhere below zero altitude.
For paladins, hollow out a large room at least 70 x 70 in a dungeon, does not have to be completely enclosed, but it does need the dungeon background. Use battle potions and water candles, then set a safe area at the top middle with platforms with honey, bonfires and heart lanterns. Sit up there, then drop down, clear spawns and fly back up, wait a few seconds and fly down, rinse and repeat. Watch for the paladin harmer to fly at you. He can quickly kill you if you are not armored enough.