My employer claims that I did not work enough hours while I was out of work on worker' comp.....even when I do go back to work I have to wait for a year for the next enrollment with enough working hours to qualify again.

Was it canceled due to the injury or due to non-payment of the premium? I've seen that happen when people are out on workers' comp and don't realize that the employer is not going to keep paying the regular insurance premium while the employee is not working.

its legal - check policy notes