A problem that occurs often is the lack of enforcement in some states when a parent willfully and intentionally violates court orders concerning visitation.
Often the enforcement at the ground level, ie. the police or sheriff, attempts to avoid the issue by claiming the problem is a “civil” matter.
So why not move it up one level?
Make it a CRIMINAL matter, so the police and DA are compelled to take action, and also make detailed reports. The other parent may start to responsibly comply with their obligations (foremost to the child/ren).
Consult your state’s penal code, and know the relevant sections before making your formal complaint.
If you have any related strategies, please do post them here.