Are family health benefits canceled when the earner goes on workmen's comp?

When my husband was married to his previous wife, they had health benefits through her union. She was injured on the job and went on workmen's compensation for 30 days until she could return to work. During that time, the insurance company cancelled ALL family health benefits because they said she didn't pay the premium through her job. Several months later, they divorced. Now the doctor/labs etc are trying to collect their fees/charges from my husband because Blue Cross rescinded all payments made to his providers while his then-wife was out on workmen's comp. Is this legal? I know nothing about workmen's comp or union benefits but it doesn't sound right to me. Thanks for your help.
Thank you, Amy Lynn for your response. I just thought it was strange that the health insurance was cancelled for only 30 days. When I was out on short term disability and my company did not suspend my benefits. I received a S/T disability check from an insurance company and my premiums were not taken out of it AND my health insurance was not cancelled. I am not sure if her insurance company is trying to get out of paying claims by pulling a fast one.
Thank you all for your responses. My husband's then-wife was injured on the job and workmen's comp paid HER bills. However, during that month her husband (now my current husbande) incurred other unrelated medical bills, and now Blue Cross has taken back its payments to HIS doctors. I guess I just never knew that health insurance for the entire famiy was cancelled when an employee is out on a job-related injury. She's still getting paid by workmen's comp, right? I just don't know. You would think that her union would of informed her about having to pay the COBRA benefits.