(CycloneTCP) - osSemaphoreWait hangs

I have installed CMSIS_RTX on my Infineon XMC4800 microcontroller (ARM Cortex M4). I have also installed CycloneTCP Tcp/Ip stack on top of it and everything compiles fine.
CycloneTCP is a free, opensource library which implements a lot of protocols.

However, when I try one of the examples comming with CycloneTCP for XMC4800, the system hangs when the tcp/ip stack is initialized at the very beginning of the code.

At some place, an OsEventCreate call is made which creates a semaphore. The semaphore is created successfully, but the call to osSemaphoreWait hangs.

bool_t osCreateEvent(OsEvent *event)
{
   //Create a binary semaphore object
   event->id = osSemaphoreCreate(&semaphoreDef, 1);

   //Check whether the returned semaphore ID is valid
   if(event->id != NULL)
   {
      //Force the specified event to the nonsignaled state
      osSemaphoreWait(event->id, 0);
...

I am using the correct drivers for my PHY and for my Ethernet Interface.

Does someone know/have the same experience why the system hangs. It seems unlogical because the call to osSemaphoreWait should return immediately when the resource is locked.

I blocks on the instruction BLX R4 in SVC_User() function in HAL_CM4.S

I have little experience in RTOS, so any help is very welcome.
I'm glad to hear it if more info is needed.