Hi @Thesis Support ,
Please check the search function related services:
Microsoft Exchange Search Host Controller Service
Microsoft Exchange Search
Make sure they are running and set to autostart.
And could you try migrating a mailbox that has this issue to another database?
I found a related thread here, check if the methods could help: https://learn.microsoft.com/en-us/answers/questions/310716/microsoft-exchange-2019-search-issues-since-cu8-an.html
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