FStorage event_handler not firing in bootloader


I am running a application that executes in the bootloader region of memory (0x70000 to end of memory), and is using FStorage to overwrite the application memory space (0x19000 to 0x40000). Ive tested a functional FStorage application in the application memory section (with correct interrupts firing), and wanted to implement the same thing in the bootloader section of memory.

In the bootloader image the fstorage_evt_handler does not fire after use, but all other related soft device interrupts /functionality (timers/UART/BLE connectivity) works fine. 

I can isolate this issue down to the bootloader project itself (no interaction with the firmware) and Fstorage does not fire its interrupts. I created a small sample project to verify this. If someone is willing to tell me where I am being stupid, I am happy to upload the sample project.