Commission after quitting??

I'm an AE currently and just accepted a new AE position at another organization. I put in my resignation and I'm continuing to work until my start date at this new company. My last day is before March 18th which is when February commissions are paid out. My commission check is supposed to be a few thousand, but I've heard from former employees that they weren't paid the commission they were owed when they left.

Is this normal? I'm wondering if I should fight for that commission or take the L and move on.