Hi,
I had a similar behavior in my code, and the problem was the amout of memory defined in the TCB, in your case, 1024.
In fact, the real root cause was the FreeRTOSConfig.h that I received when the RAKWireless libraries for boards(in my case it is a Nordic nRF52840) was installed it was wrong.
In the AWS Github has some vendors (they are a little bit old but you can compare with number that you have in your file), and ST has: FreeRTOSConfig.h for STM32l475. Maybe you can find some fixes… 
Regards,
Claudio