to replicate the issue:
First, create a recurring event in Outlook Calendar. Every Monday, Wednesday, and Friday at noon, for 1 hour. Times are not set in stone, so make them all tentative. Set no end date for recurrence, since no end date is known and the event will occur for the foreseeable future, and save.
Next, make some changes to times on a bunch of the events. Type in some notes in the events that your business depends on, and will cost you money if you lose them.
Next, try to go into the series and change the original start time to 11:30 instead of 12:00. When clicking to save changes, I get the "If you changed specific appointments in the series, your changes will be cancelled (more like DELETED FOREVER WITH NO WAY TO UNDO, let's use accurate wording here) and those appointments will match the series again" message.
Microsoft, it's 2018. Your software might be the premier gold standard for office use, but the lack of ability to do something as necessary as changing a recurring appointment without affecting all previous appointments, which have invaluable data saved in them, is a big enough issue to be a complete deal-breaker. This needs to be added to your to-do list.
Please find a way to make this happen. It isn't acceptable that I go to Google to get this functionality (at no cost to me) as a work-around. It isn't acceptable that I must manually move each event to the new adjusted time FOREVER. I cannot stop the recurrence, I cannot make a change to the time, I cannot make ANY CHANGE to the recurrence WITHOUT LOSING ALL CHANGES PERMANENTLY. Really?
That isn't an acceptable answer. WE pay you WAY TOO MUCH MONEY for that to be your answer. Please get on this.