Try the following when searches do not give expected results:

1.  Change the Filter from Modified in the last 30 days to all

2.  Click Reset which will clear all possible filters

3.  Be sure you are searching the proper column.  Case Number refers to the court docket while Matter ID is internal to StratusBK 

4.  Check the Orange Magnifier to confirm it is searching for "Contains" rather than anything else.