1. Go to legacy admin interface;

2. On "Home", create a folder "RelatedFolder", and publish it;

3. Still, on "Home", create another folder "RelaterFolder", and on the bottom, on the "Related Items", click "Add existing".
Choose the "RelatedFolder". Click on Publish next;

4. Go to PlatformUI;

5. Go to "Content -> Content structure";

6. Click on "Content tree" and click on the content "RelaterFolder";

7. Click on the tab "Related Content". You can see "RelatedFolder" listed on the "Related content" view.
If you click on the link for the related content, it will stall the loading process and on firebug's console I'll get:

Uncaught TypeError: Cannot read property 'childCount' of undefined             ez-restmodel.js:123

expanding the error I have:

(anonymous function)	@	ez-restmodel.js:123
m.each.m.forEach.p._isNative.i	@	yui-min.js:10
Y.eZ.RestModel.Y.Base.create._parseStruct	@	ez-restmodel.js:118
Y.eZ.Location.Y.Base.create._parseStruct	@	ez-locationmodel.js:35
Y.eZ.RestModel.Y.Base.create.parse	@	ez-restmodel.js:157
e.Model.e.extend._parse	@	model-min.js:8
(anonymous function)	@	model-min.js:8
XHR.onreadystatechange	@	CAPI.js:1389