Not able to update to 1.8 using one-click update

I am running PIWIK 1.7.1 and still do not see one-click update icon offering update to 1.8.

When I have installed PIWIK originally I was able to update to 1.7 and 1.7.1, however one-click update is not displaying update for 1.8. I prefer not to perform a manual update.

Any ideas?