Problem 1: Workbooks with a sheet that has all cells empty such as HiImEmpty.xlsx throws an IndexOutofRange exception on SaveToStream(). I can catch the exception to work around it, but it's a poor allocation of resources for such a common condition.
Problem 2: verticalIsBad.xlsx System.NotSupportedException (included in attached zip file) "It is not supported for this Vertical Axis type" This is unfortunate, but we can catch the exception and move on. The problem is that after this particular exception is encountered we see a significant increase in System.NullReferenceExceptions that escape the catch block and crash the application.
Included is sample code running the code with option "G" opens all three of the included files verticalisbad.xlsx and writes the exceptions that we encounter just for reference to this bug.
To re-create Problem 2: Run mode R
R mode will open veriticalisbad.xlsx then a known good file that is included and the test code prompts you for how many times you want to do this sequence. In our tests we tell it to run 10 times and by the 3rd the application usually has crashed.