Steps to reproduce:
- Create a page with this content:
- The tree is opened to the Sandbox.TestPage2 node
- Change your user's preferences and set "Display hidden documents" to Yes
- Reload the page from step 1
- The tree isn't opened to the Sandbox.TestPage2 node
Might be related to the fact that there are a maximum of 15 branches opened at once. You need to click on the Eye icon to see more.