SX1276 FSK modulation - DIO0/1 stop moving

Hi everybody,
I used for a while SX1276 in Lora modulation and everything was fine. Now I decided to switch to FSK modulation. In general things go well but randomly I’m in the condition where DIO0 and DIO1 stop moving even if there are FSK packets on air.

I can correctly receive and transmit many hundreds of packets and suddenly transceiver gets deaf even if it’s still in RX (from RegOpMode).
I’m using SX1276 Semtech driver at version 4.5.2. A way to recover is to put transceiver in sleep/stdby and then again in Rx. With this procedure FIFO is cleared and everythings come back to work. It seems to be a FIFO related problem.

In my pcb design I currently have connected SPI, Reset, DIO0 and DIO1 pin.
Any ideas of the reason why DIO0 and DIO1 stop moving and how to solve?

Thank you,