WiX Bootstrapper ShowFilesInUse shows app name as "A" - wix

Question

I have a bootstrapper WiX project which can run a x86 or x64 MSI, depending on CPU. It works well. I set the ShowFilesInUse to "yes" so WiX can optionally kill running app or require restart.
However, if the app is running, the dialog shows the app name always as just "A" instead of the actual app name.
Just "A" nothing else. In the Task Manager my running app clearly shows it has a name of "My App" or MyApp.exe.
I'm not sure what I'm missing here.
<?xml version="1.0" encoding="UTF-8"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi" xmlns:bal="http://schemas.microsoft.com/wix/BalExtension" xmlns:util="http://schemas.microsoft.com/wix/UtilExtension">
<?include $(sys.CURRENTDIR)\..\MyApp\WIX_Version.wxi?>
<?include $(sys.CURRENTDIR)\..\WiXSetup x64\Variables.wxi?>
<Bundle Name="My App" Version="$(var.ProductVersion)" Manufacturer="My Company LLC" UpgradeCode="$(var.UpgradeCode)" AboutUrl="http://www.mywebsite.com/tools/MyApp" IconSourceFile="..\Graphics\ApplicationLogo.ico">
<Variable Name="InstallFolder" Type="string" Value="" />
<BootstrapperApplicationRef Id="WixStandardBootstrapperApplication.RtfLargeLicense">
<bal:WixStandardBootstrapperApplication LicenseFile="..\MyApp\EULA.rtf" LogoFile="..\Graphics\InstallerLogo_64.png" ShowVersion="yes" ShowFilesInUse="yes" />
</BootstrapperApplicationRef>
<Chain>
<MsiPackage Id="x86" InstallCondition="NOT VersionNT64" SourceFile="$(var.WiXSetup x86.TargetDir)MyAppSetup_x86.msi">
<MsiProperty Name="INSTALLFOLDER" Value="[InstallFolder]" />
</MsiPackage>
<MsiPackage Id="x64" InstallCondition="VersionNT64" SourceFile="$(var.WiXSetup x64.TargetDir)MyAppSetup_x64.msi">
<MsiProperty Name="INSTALLFOLDER" Value="[InstallFolder]" />
</MsiPackage>
</Chain>
</Bundle>
</Wix>