Hang up issue when using WebView2Runtime109.*

Hi,
I’m seeing some hanging up issues when using a particular runtime version of WebView2 with my project. If possible would you please look into this issue?
In my project, I’m using WebView for UI and previously using Trident and now trying to move to WebView2.
As you know, WebView2 runs processes such as creating WebView or calling JavaScript non-synchronous, but as for convenience of existing implementation, I’m running it synchronized by using a modal loop.
Although, a particular version of runtime hangs up because control does not return by this modal loop.

As I investigate, this issue is happening because of 2 things.
1.My implementation of modal loop during synchronization does not return the control until all messages have gone from the stack.
2.Looks like messages keep sending (maybe from WebView2?) during the modal loop.
Content of these messages is “0x403”.

Also, looks like this issue will be clear when getting out from the modal loop.
I can modify the modal loop of synchronized process, but for the other existing modal loops are difficult to change so if possible I want to find a way to clear the second cause which I described in the above.

Questions:
1.Do you have any information about this “0x403” which is sent continuously?
2.What is the trigger of this message? Do you know the purpose of this?
3.As I checked this issue won’t happen in the runtime after version 110.
Is this an existing issue which is already solved? If so, the latest version of runtime would never get this issue?

Environment:
OS: Windows 10 Pro / 21H2 / 19045.2965
Framework: Win32 C++
Runtime: 109.0.1518.78
SDK: 1.0.992.28

If it is necessary I will send an execute file so please let me know.