Is there a maximum number of contacts in an Address Book group?

Question

I have 4,367 contacts. I'm trying to create two different groups, one for my wife and one for me. The majority of the 4,367 contacts will be in my group.
I've tried several time but keep getting the same result.
On the iCloud website I create a new group with my name.
I copy several letters worth of names (say the As through the Cs) from All Contacts lists to the David list.
Everything works fine until I finish the Rs, with about 3,800 contacts. I've tried it signing in and out and everything sticks and looks fine.
From then on every name I add appears under the R banner (see below) and, once I sign out and sign back in, disappears.
Any ideas would be much appreciated.
I'm using a 6 month old 3.06 GHz Intel Core i3 running OS 10.7.4. Not experiencing problems in any other area.

Answer 1

Thanks for the link. I don't think it's a space issue. When I look at my iCloud account through System Preferences it shows that I've got 24.99GB of 25GB available (it's just the Contacts and a personal Calendar).
The rules on limits, though, are really confusing. Total number of contacts 25,000 - I can understand that. Maximum size of a contact card 256KB - ok, I see how if you have War and Peace in the notes section that would be a problem. But what does it mean that maximum size of a contact group is 256KB? That's the same size limit as a single card so I assume they're referring to the size of the list of contact cards in the group. But how many contact cards equals 224KB?!? Based on experience, I'm guessing it equals about 3,800 contact names (which frankly doesn't seem like a lot to me - I've been collecting contacts since I got my first Palm Pilot in 1996, which comes to around 225 names a year, not a lot if you're in business).
Anyway, thanks for the help. If I run across a solution somewhere, I'll post it.