That's the issue iI mentioned before: as soon as the heigth of block 2 is more than that of block 3 this will happen: block 4 is then positioned 'to the right' of block 2 instead of below it...
The longer text in block 2 (1) wraps earlier than that in block 3.
As a result block 2 is 'higher' (2) and pushes block 4 to the right (3).
Solution: make sure that the text in block 3 is the same of more than in block 2...
No other way to fix it now: The css grid I made for TP 2.1.0 will deal with this...