doublespaces
Well-known member
Ensure you don't have noscript or some sort of adblocker enabled when browsing the XF admincp. This works for me on multiple sites hosted on several platforms, across dozens of add-on installs.
Check for any console errors, or network failures by hitting F12, refreshing the install page and trying again.
I've disabled adblocker and also turned off kaspersky. There are no console errors. I've even reinstalled XenForo on a test bed.