Just Upgraded to 5.6 from 5.5 and Can't set Block Permissions

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I just upgraded from 5.5.2.1 to 5.6.2.1 to see if I couldn't give editors access to stacks without giving them full admin rights. But now none of the website editors can add a block to their pages.

I went to the dashboard -> Block & Stack Permissions. Add block shows just "administrators". I want to add the "editors" group to this. I go through the add included dialog, select the 'editors' group, then click save. At this point I get a funny dialog box.

Title: Message from webpage
Contents: Yellow triangle with exclamation and the number '3', and an OK button.

If I click OK, then I get a second dialog box.

Title: Message form webpage
Contents: Yellow triangle with exclamation and the number '0' this time, and an OK button.

After hitting OK, nothing happens.

Any help?

iHSSports