Adding a winterbreak holiday for players

I'm a bit stuck in my latest database (creating the new dutch structure from scratch) and I got almost everything going (including period groups and playoffs for lower divisions etc) but I can't seem to fix one problem and I do remember that I could add this in earlier versions of FM (FM12 or 13?) but I can't seem to remember how. It's not that big of a deal but I can't stand it though because the problem is as follows:

In Holland we have a winter break like almost every other country and I have created a winter break from 23 december until ~15 january but the game does not add the player's holiday that they have from 23 dec until january 1st. Because they have one irl and is followed up by a friendly period until the competition resumes mid january.

I've tried adding a mid-season break period through the advanced rules' nation but it does not seem to work. Take in mind that I've created the leagues from scratch and have nation rules override all rules selected.

Try it by adding two winter breaks:

1. 23. dez until 3. Jan. --> mid season break

2. 3. Jan. until 15. Jan. --> mid season big friendly period

Unfortunately it didn't help. I've seen ingame that the belgian competition does have a winter break but I can't find anything when I'm trying to reverse engineer that competition. It's not a dealbreaker but I don't know what to do unless you have another option for me to try out.