DWM3000 get status_reg value

I have strange behaviour on two modules;
On the Makerfabs evaluation kit, with the sw example “ds_twr_initiator”,
after first TX start, there is an initial read of status


        /* We assume that the transmission is achieved correctly, poll for 
         * reception of a frame or error/timeout. See NOTE 10 below. */
        while (!((status_reg = dwt_read32bitreg(SYS_STATUS_ID)) & 
                                               (SYS_STATUS_RXFCG_BIT_MASK | 
                                                SYS_STATUS_ALL_RX_TO      | 
        {   /* spin  */   };

which usually do not cause delays.
The same Initiator code on my own pcb, with newer (I guess) DWM3000, in the same point
at the first round, the program hangs in the While loop for about 18 sec…
then proceed normally, also in the subsequent loops…

On the DWM3000 of Makerfabs pcb, the status_reg value, before and after the first TX is always 0x1800017 without delays,
while on my pcb the value before first TX is 0x9800007 and take 18 sec. to become 0x1800017 and proceed.
After this initial problem, the example works fine on both PCB…
With the same source code (apart some pins adjustment for the SPI lines) the only difference I can see is the module DWM3000.
Anyone have an idea or suggestion to reset the status to 0x1800017 before starting TX ?

Best regards,