I think I may have deleted a bunch of activities by accident. Here's what seems to have happened:
I had "Activity X" scheduled to occur every Saturday from 6/10/17 to 12/30/17
As 2017 rolled along, each Activity was customized as a stand-alone "just this one" edit week by week. This gave me lots of individual past activities as desired.
Because I needed to keep doing this through 3/31/18, I went to the entry for 12/30/17 and extended its "stop repeating" date to 3/31/18 and noted to apply only to this instance forward.
This preserved the 12/30/17 instance (correct), created the weekly activities through 3/31/18 (correct), but seems to have made all activities in the set prior to 12/30/17 disappear (ARRRGH)!
Any idea what may have gone wrong and how to recover? What I described above is actually the situation for about 300 activities all together (I just gave one example).
We use WordPress and latest Civi edition. Thanks.
P.S. We may have a backup, but if this is a bug or something unclear, I want to be sure others know.