Piggy backing off this thread, I'm seeing add new page (vs. Lassi's add new block) being grayed out under particular pages in my tree structure despite access rights being in order. Copy and paste works for me as well.

Hi William, did you ever find out what was wrong? I think I'm experiencing the same thing.

I've got the same problem. Access rights seems correct.

We came across this problem yesterday. We could not click "New page" in the page tree, it was disabled. We could however copy pages.

After double checking access rights we were at a loss regarding what the cause would be.

However, we had 7 different sites under Root and two of them (including the one with the problem) used the same language. By clicking on the StartPage for the problematic site and then on the plus icon for "Create content" on the top of the page we could see that we couldn't select any of the pages under the problematic site, we could however select the pages on the site with the same language.

Clicking on each node generated a request with a JSON-response, the request URL looked like this:

/episerver/cms/Stores/contentstructure/?referenceId=12180&query=getchildren&typeIdentifiers=episerver.core.pagedata&sort()&dojo.preventCache=1444808983754

By comparing the JSON-response from one of the nodes we could select with one that we couldn't we saw that the site that worked properly gave us "isPreferredLanguageAvailable":true whilst the site that didn't gave us "isPreferredLanguageAvailable":false.

We therefore went to the StartPage of the site that didn't work -> Tools -> Language Settings and could see that there was no language set. One of the editors of the site must have unchecked "Inherit settings from the parent page: Root". We enabled this setting and now we can create pages again.