Hi @mark goldin ,
According to your description, considering the impact of some add ins, It is suggested that you could try to start outlook in safe mode(win+R>type: outlook /safe) to check whether it works normally.
If this is still the issue in safe mode, it is suggested that you could try to create a new profile(Control panel>Mail>Show profiles>Add>type the name for the new profile>OK) and add the account again to check if there are some differences.
Hope to help you! If your issue has any update, please feel free to post back.
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