His mom eventually see his side of thing and is supportive, but Dad never seem so.
One day they get into an argument and Lutz ran to the temple, even considering becoming an orphan so he's no longer 'controlled' by his family.
Benno even considered adopting Lutz to inherit Gilberta company.
Myne had the temple intervene to call them for a family discussion, where both side get to say their pieces with Ferdinand and Myne being there to help mediate things.
tl;dr? It's...a misunderstanding.
Lutz thought his dad was being dismissive of his choice of career.
But it's just his dad being bad at speaking, so when the dad said "do whatever you want", it wasn't 'whatever' dismissing of Lutz decision, it's literally giving permission for Lutz to follow his dream.
After that the family reconcile and there's no more problem.