Htaccess can create problems if any of your GET parameters have the character Ampersand (&) even though it is urlencoded.
For example I have a get parameter called Apple&Orange when I urlencode it the Ampersand (&) symbol will be converted to %26. And this will work fine in dynamic urls like :
But in htaccess in order to produce clean urls we may have used like :
So the tag parameter in the receiving page will be Apple instead of Apple&Orange.
Adding B flag will solve this issue in htaccess.