This is another one of those weird ones. Marijuana Mix Infused is the category often used for items such as moon rocks or joints that have some type of concentrate included, such as CO2 Oil or Kief.
Unfortunately, the LCB requires all combined items(flower lot, kief, ect) to be first individually QA tested, and then QA tested again after conversion into MJ Mix infused, so make sure you’re creating enough units to make it worth your while.
Make a Plan! Write down the following:
How many units do you want to create? [let’s make 1000 units of Infused Joints]
What are the last four digits or your ingredients? (or you can find them via the search bar and filters etc) [Let’s use some Flower Lot, some co2 oil or whatever you want to mix together]
What is the Net Weight of a finished unit? [let’s use 0.75 grams]
Click the "convert" button on the inventory overview page
Choose a Type you’re making [MJ Mix Infused] or GrowFlow product
Select your ingredients and enter their weights to be deducted
Enter Quantity of finished units you’re making. 
Choose a Product Name etc
Make sure you do not use the skip testing check box
Your new inventory will now be visible on the inventory overview page.
Done! Now create a QA order to get your MJ Mix Infused inventory QA tested by your lab.