Thanks, Josh, but the casts are set to go out at BST (my location) and we have a different engagement program for each region, set to the appropriate time BST that maps to the local time. This was all working and going out correctly until mid-March, which makes me wonder if something in the March release broke the timings.
Regarding the query about the stats, there are two possible issues:
1. I am switching entire engagement programs off some weeks (in order to execute other marketing campaigns). I was wondering whether this somehow messes up the cast timing calculations when it then gets turned back on
2. If I reset the cast start date, that is what was concerning me about the statistics, not pausing leads or deactivating content.