The “Resetting prediction variance” error is a severe error - it indicates the host software was unable to make accurate predictions of the micro-controller clock. Oddly, it was the “linux mcu” running on the host that was having the synchronization problem. I suspect this might occur if the system clock has an incorrect time and the system ntp process is struggling to correct the time.
I’d try commenting out the “mcu rpi” and “adxl345” config sections to see if that resolves the immediate problem. Also, you might want to check if the rpi system time is accurate.
-Kevin