Dear Allmon,
Thanks for choosing Microsoft Community.
Based on your description, I know the the ssue you met. Coule you please be kindly to tell me whether the appointments you can only open series were created by ourself or others? To better help you, I did a further test for you but through my test ,in fact, if the appointments were created by others and then assigned to you. There will be an option let the creater to choose whether let people only open the appointments series or only open occurrence or both.
If the appointments were created by yourself and you meth such problem, it may have somthing wrong with your outlook client. Please be kindly to try to Repair an Office application and then check the result.
If the issue persists, please be kindly to provide the screenshot sbout your outlook version by clicking FIle>Office Account>About outlook. I will continue to help you based on the information you provide, Your understanding and co-opeartion are highly appreciated.
the option of "open occurrence vs open series". Thanks for your precious time. Have a nice day.
Sincerely,
Katherine