at the first glance I see that you doesn’t execute dwt_forcetrxoff() on Rx error as in the sample ISR by Decawave.
Furthermore, I think that your problem might be related to the one I’ve experienced:
You wrote that you are also transmitting, IMHO it is possible that this Rx re-enable problem after Tx causes this Rx timeout malfunction too. My workaround seems to solve this problem, so you may implement it to your code.
