Calendar sync seems to be limited

Hello,

I'm using Zextras 1.2.5 on Zimbra 7.1.4.
My phone is a Samsung Galaxy SII running Android 4.0.4 under CyanogenMod 9-20120329-NIGHTLY-galaxys2.

I know what Cine will say about Cyanogen Nightly, but it's very stable so far

The problem I've encountered is the apparent limitation on numbers of calendar event which is sync to the phone.
When I browse 3 weeks forward or next month, I can see only recuring events but no non-recuring ones.

Switching sync days (I believe this is just for email) to "One month" or "All" is not a solution for me as the amount of data to sync is too big (lot's of emails).

What do you think I should do ? Any tweak ? Or report the bug ?