If there were a minimum amount of wages needed for FICA withholding, it would surely be well below $50,000!
There may be some exceptions for students (but that would probably be inconsistent with there having been $50,000 reportable income) or for certain kinds of non-covered governmental work (i.e., if the employer is a governmental entity not participating in Social Security). Would either of those apply?
Otherwise, how could someone earn $50,000 and not pay FICA taxes?