Same issue here. Even all the index repairing tipps in the net, don't solve the problem. Using Outlook with in Exchange Server.

Same issue on my new MacBook Pro 14'' an Monterey 12.1. On my old MacBook and BigSur everything still works fine with the same Outlook Version. So I believe it must be an apple problem. Regarding to that I will use my old MacBook until the problem will be solved ;-(