Found a way to diagnose this issue. Through a Google search, found instructions to open diagnostic summary data in Windows:
Settings > Privacy > Diagnostics & feedback. Scroll down to "View Diagnostic Data", turn the setting on, then click on Open Diagnostic Viewer. This will take you to the Windows store, download the app and install.
Clicked on the "Problem Reports" left hand menu pick, scrolled down and found many entries for Search Application, all like this:
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Search application
Description
Faulting Application Path: C:\Windows\SystemApps\Microsoft.Windows.Search_cw5n1h2txyewy\SearchApp.exe
Creation Time: 12/8/2021 2:17:28 PM
Problem: Stopped working
Status: Report sent
Problem signature
Problem Event Name: MoAppCrash
Package Full Name: Microsoft.Windows.Search_1.14.2.19041_neutral_neutral_cw5n1h2txyewy
Application Name: praid:CortanaUI
Application Version: 10.0.19041.1320
Application Timestamp: bdfaf044
Fault Module Name: combase.dll
Fault Module Version: 10.0.19041.1348
Fault Module Timestamp: baf10630
Exception Code: 80070543
Exception Offset: 00000000000862a6
Extra information about the problem
Bucket ID: b8245a700e899c43668c574363557344 (1624769512514876228)
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That exception code is in winerror.h, translates to "Cannot open an anonymous level security token".
Searched on that, found this little gem: http://ctimls.com/Support/KB/Error%20Fixes/Fix_Login_errors.htm
"Cannot Open an Anonymous Level Security Token
To fix a "Cannot open an anonymous level security token" browser error:
Open the Windows Control Panel
select Administrative Tools
double-click on to open Component Services (in the List)
double-click on (or click the + beside) Component Svcs (in the white box)
double-click Computers
right-click My Computer
select Properties
select Default Properties tab
change the Default Authentication Level to "Connect"
change the Impersonation level to "Identify"
click the OK button. "
My setting had Authentication Level as "None". Changed to "Connect", problem solved.