Thanks for creating a new thread for issue you are facing.
Please confirm when you do simulation in CU50 its resulting in correct material variant determination. As in screen shot i can see BOM with only one component but i cant see the material variant.
use Transaction: CS40 for creating link material variant to configurable material BOM.
Also , please check you BOM usage and BOM application tied up with your production order type, it may possible in simulation its using PP01 but in production order it may belooking for another BOM usage and resulting in NO BOM .
If you have recently changed any on the settings please create a new setup, like create new sales order with KMAT resulting in material variant replacing the sales order line item and then run MRP to get plan order followed by production order , it may work.
To check the possibility of class node creating this issue, just add an normal component in BOM , just for test, it may help you as even if class node is not getting replaced a normal non configurable component will always appear and atlest it will prove BOM explosion for your production order works fine.
Please check and revert back. Hope it may help you.
Thanks
Ritesh