2:59 AM
@user574848 I will check it now...

2 hours later…
5:29 AM
Just fixed it, the server is on.
I have to say the user queries are really good test-cases. I always find a new bug on each server fault :-)
Now I believe v3 is getting much robust, I would be disappointed if the next day the server goes down again.

3 hours later…
8:44 AM
@WeiZhong: Just mentioning that $\frac 14$ and ${1 \over 4}$ give completely different results.

1 hour later…
10:03 AM
@MartinR Thank you, I can confirm this is unexpected behavior. This problem will occur when you use \frac followed by two consecutive numbers without space, and there is an "one" in either numerator or denominator. I will fix it, however, because re-indexing the entire corpus costs a lot of time, I will let you know when the official site index gets updated, at that time the changes will be reflected.
thanks again for reporting this issue.