Is the OpenThread API concurrent safe?

[CMasc.1]

I am developing a FreeRTOS project with around 12 tasks, many of which use the open thread ot* functions. However, my program will occasionally deadlock on all OpenThread commands, with the stack for each task showing that it is waiting for "Wait_Getting_Ack_From_M0" to finish.

I believe this is related to attempting to concurrently use OpenThread functions within multiple tasks. Is there any documentation or guidance from STM on whether gating OpenThread functions with a mutex is necessary?