Text boxes in master pages

[duncanl22556443]

I'm an InDesign novice, but I'm losing my mind here. I just need to have a dropped chapter master, so with a text box that doesn't go all the way up to the upper margin. When I create this master and apply it to the relevant pages, I can see a dotted line where the text box should be, but the flowed text ignores it. I've done this before but cannot for the life of me remember how. Can anyone help please? 

[rob day]

Are you using Primary text frames for the running text? If not this might help:

https://community.adobe.com/t5/indesign/can-someone-help-demystify-how-primary-text-frames-actually-...

[duncanl22556443]

Yep, but when I apply the master I only see the text box as a dotted line and it doesn't affect the text. I can adjust the margins on the master, but not sure that's how it should be done?

[rob day]

Check that the text flow is really flowing through Primary Text Frames. There can only be one per master page and they have a unique icon when selected:

Here the text flow is running through Primary Frames and I have a duplicate B Master where I’ve adjusted the frame size:

Dragging a B Master onto page 3 which converts it from A to B, while keeping the Primary text flow