For some reason, many of my recurring meetings have the "show as" field grayed out so I can not change it.
According to my tests, the 'show as' field grayed out issue may happen after you have changed the meeting on its own, such as accept it only or change the 'show as' status by opening the meeting individually like below.(double-click the meeting>just this one>change 'show as'>save), Have you performed above operations?
Actually, I tried to create a customed view and change the 'show as' filed of a meeting in the recurrence , it won't work as same as your situation. So, the status of recurrence meetings may be a whole and cannot change due to a single meeting settings, whatever you change the 'show as' or accept it, which may result in this issue.
If you want to show part of the recurrence meetings in your customed view, I'm afraid that you could only accept and change the status of whole recurrence meetings firstly and deny or delete the several meetings you don't want to accept or show on your calendar, which may be laborious but effective.
Hope the above information is helpful to you.