No reference to a CAO in the employment agreement? A CAO may still apply.
A Dutch employment agreement can contain no reference to a collective labor agreement and still be subject to one. Whether a collective labor agreement (CAO) applies can follow from the activities performed by the business.
Your employee also works elsewhere. When does that become your compliance problem?
Your own schedule may look perfectly compliant in isolation. But work performed for another employer can affect compliance with the Dutch Working Hours Act and can become an employer problem.
When a sick employee does not cooperate: can you stop paying salary?
Continuing to pay salary may seem like the cautious approach. Under Dutch employment law, however, failing to act when an employee does not cooperate with reintegration can create a risk of its own.