There
should be an Easter version of "Collect All":
though clearly there should also be Eggs to find.
There's a hypothesis running in the German forum that it may have to do with whether or not the person being buffed is online at the time. This doesn't seem always to affect it but it's worth keeping mind just in case. For now, if you've tried all the standard "Refresh, clear cache & cookies, log out completely..." and still nothing Support is probably your best option:
http://www.thesettlersonline.com/en/help-and-support