Hi Lindsay,

I installed 2.4.2 and tried to reproduce this but have not been able to.  The only suggestion I have at this point is to take a look at the extent control and test using the Current display extent and Same as layer options.  Also make sure you have no selections in the map when converting labels to annotation.  If none of those resolve the issue please contact technical support as they will be able to go through this step by step and with your data if needed.

thanks

Wendy