Troubleshooting Traffic Graph Behavior in mwan3 MultiWAN

Hello. I always get a lot of information and help here. I have a lot to learn in this field. I'm eagerly awaiting a response. Please help.
I've set up a policy using the mwan3 package in a multiwan environment.
When I have wan1, wan2, and wna3, I want to prioritize them in the following way without using the load balancing feature:
wan1 has priority 1, wan2 has priority 2, and wan3 has priority 3.
In other words, when all three, wan1, wan2, and wan3, are connected, I want only wan1 to be used (100% usage on wan1) and the others (wan2, wan3) to be unused.
When only wan2 and wan3 are connected, I want only wan2 to be used since it has a higher priority than wan3.
To achieve this, I've configured the metrics and weights as follows:
wan1: Metric 10, Weight 3
wan2: Metric 20, Weight 2
wan3: Metric 30, Weight 1
I've set the policy to 'wan1_wan2_wan3'.

I conducted a test under the following conditions:
wan1 is not connected to the network, but wan2 and wan3 are connected.
In this case, only wan2 should be used at 100%.

However, strangely, in the "Status" menu of LuCI, under "Realtime Graphs" in the "Traffic" menu, the graph for eth3 continues to operate.
Theoretically, since only wan2 (eth2) should be in use, wan3 (eth3) should not be active, but why does the graph for eth3 show continuous traffic?

Could it be that I've misconfigured the policy? Or is the network switch not happening 100% as intended in mwan3?

The purpose of my project is to ensure that when network switching occurs, other networks are not used. This is to minimize packet communication and achieve network switching based on priorities. I've used mwan3 for this purpose, but it seems like a seamless network switch isn't happening. I welcome suggestions from anyone who has a better idea. Your assistance is greatly appreciated. Thank you.