iOS Exchange set up - limited to 50 contacts?

iOS Exchange set up - limited to 50 contacts?

I am currently using a free Zoho email account with my own domain. Email is being pushed nicely to a standard Exchange set up on my iPhone (via msync.zoho.com) but when I try and sync my 168 contacts I only ever get the first 50 and then it refuses to sync any more.
NB. If I load up the Zoho app itself then all my contacts show correctly.

I have tried this on my iPhone and iPad multiple times, I.E. removing the Exchange account, rebooting and then adding back in again.

Is this a limit with the free account, has something gone wrong or am I misunderstanding something?

Thanks,
Steve.