I don’t think that this rather strange effect is caused by FreeRTOS in itself, but I found this interesting post in the STM32 MCU forum.
Seems that certain programming bugs (e.g. writing to address 0 and upwards) cause FLASH_SR_CFGBSY being set on a STM32WB55…
It would be better if accessing/writing to a NULL pointer would cause a far less misleading hard fault 
Maybe you stumbled into a similar issue accessing a not yet initialized HAL (peripheral) handle or it’s something different…
I guess you’re using TIM1 as FreeRTOS ticker and not the SysTick (probably used by HAL), right ?
Also see this interesting thread here in the forum. It seems to me that there a still a few issues running Cube-generated FreeRTOS apps on the STM32WB55.