Setting a Block Style Returns a Page Not Found

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I am not sure if anyone else has this issue, but when I choose a block, select "Design" and then set a block style, when I click save, the busy indicator shows for a while (10-20 seconds) and then I get a page not found error. If I refresh, the page redisplays in Edit Mode and my block is styled as expected.

Thanks!

# concrete5 Version
5.6.1.2

jmcgarvey