Using classic Outlook for Windows in business environments
May not be the same root cause as for CSal, but I also had this problem. Found this post and after playing around with it a bit more I noticed that while everything was grayed out in the same way, on the right click menu, and the Ribbon bar, I noted that on the Ribbon next to the grayed-out items was the "Edit Series" option. I clicked on this and was able to change the meeting to Show as I wanted and it changed once I "Saved" using the File option on the Ribbon or the save icon.
After clicking on "Edit Series" and the meeting opens
Saving with ...
or
Hope this helps.