Since yesterday I've been having issues. Today I tried to preview an email and I click and nothing happens. Yesterday it was a form I tried to preview and nothing happened. Also, I tried to edit. It doesn't seem to matter if I right click on the asset and select the feature or use the button on the right side of the page.
Not sure if its just me or my computer or my network or what.
Pop-up blocker, maybe (since the designer opens in a new tab on a new sub-domain)? Chrome does this to me all the time until I whitelist the Marketo domain.