Device hangs if it receives a scheduled (confirmed) downlink message before the first wakeup

I am using a custom board with the murata ABZ chip (STM32L0 series), I am sending and receiving successfully at any other time except when the device first starts.

If there is a scheduled downlink message before the device starts then, I can see from the network the ACK that the message has been received but my device freezes I am using CLASS C, but if I am using CLASS A then this works, I am currently changing from class A to class C at a later stage( I want to use class C in my project).

Why is this happening?

No source file, test, or entry point is named. Start by reproducing the startup sequence on the custom Murata ABZ STM32L0 board with a scheduled confirmed downlink, comparing Class C and Class A behavior; done means identifying why Class C freezes before the first wakeup and documenting the cause.

Written by the indexing model from the issue text.