That sounds like a problem with the target application itself.  When working
with and troubleshooting the UI Automation stuff, it can be quite helpful to
make use of some of the tools provided with the Microsoft Platform SDK, e.g.:

    %ProgramFiles%\Windows Kits\10\bin\x86\AccChecker\acccheckui.exe
    %ProgramFiles%\Windows Kits\10\bin\x86\accevent.exe
    %ProgramFiles%\Windows Kits\10\bin\x86\UIAVerify\VisualUIAVerifyNative.exe