Can't join objects with different materials I'm trying to join multiple objects with different materials(Ctrl+J). When I join them they disappear in render view.
I was trying to assign materials to different mashes, but it doesn't work!
I just don't know what to do

This is my blender file:
https://drive.google.com/open?id=1w6xj5XGGIMKtyS8n-4XUSqpCFBkTOaAx

There is flower model and 4 materials: green for flower stem, flower leafs and flowers

I joined flower stem,leafs and flowers but it shows only flower stem in render view.

edit: sorry, I forget to pack textures into .blend file
So...
When you want to join multiple objects, be sure that they have UV maps with identical names.
It was not obvious for me.