Since about 2/10/2023, Outlook 2021 Search function doesn't show recent emails under Windows 11. It will often show one current result (within the past few days), followed by results dated not-later-than 5/21/2021.
Recent Windows updates are:
KB4023057 installed 2/20/23
KB5012170 installed 2/20/23
KB5022836 installed 2/16/23
KB5022730 installed 2/16/23
KB4023057 installed 1/19/23
This copy of Outlook is part of MS Office Home and Business 2021 - Update #16.0.16026.20146 was installed 2/17/23
I ran SCANPST on the OST file multiple times and each time it reported that "Only  minor inconsistencies were found" and "Repairing the file is optional".