I have a tried and tested tip that will help you collect all the materials that you are struggling to find!
No matter which item you are trying to collect, this tip will work!
What you need to do:
After you have set your character to complete the item earning task at least 5 times, set the character (or characters) to complete an hour task, then set your character to complete the item earning task again – once this character has completed their task, the item you are wanting should drop!
Other players that I have shared this tip with have replied back and told me it has worked for them, so I thought I would share this tip with all of you!
Let me know if you try it and it works!