some F3 info shows as "??"

I don't know if this sould be just in MC, but as it only affects my realms server i made this issue here.
A friend of mine had a minecraft realms server and downloaded the world so i can host it now because he doesn't play anymore.
but now when i press F3 i don't get some of the info i need (shown in a screenshot), instead it appears as "??". Also doesn't show "(day XXX)".
This problem didn't exist in the original realms.