Wpf app crashing - Faulting module name coreclr.dll version: 4.700.20.47201

I have WPF application on .netcore 3.1 packed in appx package and installed from the package. Sometimes (one on several dozen starts) it crashes on startup with errors in EventViewer:

first error entry:

Application: MyApp.exe
CoreCLR Version: 4.700.20.47201
.NET Core Version: 3.1.9
Description: The process was terminated due to an internal error in the .NET Runtime at IP 00007FFE0C06FF20 (00007FFE0C050000) with exit code 80131506.

next error entry:

Faulting application name: MyApp.exe, version: 1.0.0.0, time stamp: 0x5f6b3998
Faulting module name: coreclr.dll, version: 4.700.20.47201, time stamp: 0x5f6a7a28
Exception code: 0xc0000005
Fault offset: 0x000000000001ff20
Faulting process id: 0x5920
Faulting application start time: 0x01d6ca611262b108
Faulting application path: C:\Program Files\WindowsApps\MyPublisher.MyApp_1.1.166.0_x64__k3e1zgp7z7sz2\MyApp\MyApp.exe
Faulting module path: C:\Program Files\WindowsApps\MyPublisher.MyApp_1.1.166.0_x64__k3e1zgp7z7sz2\MyApp\coreclr.dll
Report Id: 0b0ae2f1-0a4c-439a-a4cd-4700425d3f41
Faulting package full name: MyPublisher.MyApp_1.1.166.0_x64__k3e1zgp7z7sz2
Faulting package-relative application ID: App

Does anyone have any ideas on how to work through this problem?