Rendering bugs and compass bugs

I'm having a lot of strange situations happening in my Minecraft for Windows 10 gameplay.

First, the compass no longer works when I am traveling by boat on water. it points in a different direction of where my spawn is and when I look towards it the pointer starts spinning in different directions.

Second, in my Norse Mythology mash-up, the majority of mob textures are not rendering. The vast majority of the mobs, such zombies, skeletons, husks, endermen, pigs, cows, witches etc are not rendering the entire mob. In some cases, like pigs, the mob is almost invisible, only beeing observable some pixels of its body. Moreover on this particular mash-up I get an error message, shown by a red exclamation mark on the Pack activation menu that states the following error:
ui/ui_common.json: Não foi possível encontrar o controlo: pocket_ui_container_selectable_slot_item/item_cell

I would like to know how can this problems be fixed, and I hope that the money I spent on the mash-up wasn't in something that no longer works.

Thanks in advance