Is the Homegrown icon showing in squad view?
I have tried al possible combinations and I'm unable to get it working.
The state of Santini on your screenshots are also true in my case, but the player isn't "really" marked as homegrown.
You are able to see that in the squad view. I have added a screenshot to show what we are looking for.
I've also tried removing the 0-15y old relation to exactly reflect your situation but it does not change Bruno's homegrown status.
De Belder has a legit homegrown status (shown by the HGN-icon), Bruno doesn't have it but has the same relations. (tried different ones + the workaround from FMRTE18, using the 'developed at country'-relation)