what reasons cause "Could not process mesh packet"?

Hi all,

development software: nrf5_SDK_for_Mesh_v2.1.1_src\examples\light_switch\proxy_server Board 1
nrf5_SDK_for_Mesh_v2.1.1_src\examples\serial Board 2
IDEs: SEGGER Embedded Studio 3.30
SoftDevices: nRF5_SDK_15.0.0_a53641a
Computer platform: Windows10
hardware: NRF52832 QFN48 DK

Step 1. I use PYACI provision and configuration Board 1 success, i can turn on and turn off the LED in Board 1.
Step 2. I close the PYACI window and open it again, reboot Board 2, recover the database to Board 2.

Step 3. When i send CMD to turn on the Board 1 LED, Board 1 can't execute this CMD, then i send the CMD continuous,
after a while it can control Board 1 LED normally.

I got the log in Board 1 debug terminal, it show "<t: 9685356>, nrf_mesh.c, 138, [er5] Could not process mesh packet..."

NOTE: After step 2, If i reboot the board 1, i can send CMD to turn on Board 1 LED immediately.

Could you help me to explain this phenomenon? And what cause "<t: 9685356>, nrf_mesh.c, 138, [er5] Could not process mesh packet..."?

Best regard!