Why is 〇 used instead of 零 in time lessons?
I noticed that in the time lessons in Chinese the character for 0 appears to be 〇 instead of 零. This is confusing because in the notes it lists the character as 零, and when I click the 〇 character in lessons, it does not have a sound (as well as when the sentence is read) which tends to throw me off a lot. Is there a way to fix this issue? I have tried reporting it, but I haven't received any replies from the Duolingo team or noticed any changes made to this feature.
Anyway, let me know what you think in the comments!
Edit: Please add audio if possible as it gets really annoying to listen to the breaks in the speech and it is unnatural as well.
When signing dates in certain situations, such as on announcements or in letters, 〇 (different than O) is used instead of 零 in the year, e.g. 二〇一八年五月八日 for today's date (May 8, 2018). Notice that the date is written as said, "erlingyiba nian, wu yue, ba ri/hao" (though you would generally write 日 here even if reading as 号) and not as “两千一百十八”! When typing, 〇 can be found under "ling".
On the difference in usage between 0, 零 and 〇: