Employer subsidized plans are also mostly compliant with ACA. Based on the trends in figure 13.3, I might even say less than 10% of Americans with employer subsidized health insurance are in non ACA compliant plans.
If you bring up a complaint, it's no longer a preventative check-up, it's addressing a complaint, which has a different billing code and different reimbursement.
The only way to guarantee a free annual checkup is to go in, say nothing about your state of health, let the dr take your vitals and leave.