The antonyms for the phrase "was stuck on" are numerous and depend on the context in which the phrase is being used. For example, if "was stuck on" was referring to a problem or puzzle, antonyms could be "solved," "figured out," or "cracked." If it was referring to a stagnant or unproductive situation, antonyms could include "moving forward," "progressing," or "advancing." Alternatives to "was stuck on" could be "unfettered," "unrestrained," "liberated," or "free." It all comes down to the specific usage of the phrase and what the context requires.