Creating New Sync/Mailing List - doesn't upload contacts from CRM

Creating New Sync/Mailing List - doesn't upload contacts from CRM

Hello, 
as written in the subject line I have problems with fetching the data from Zoho CRM when creating new Sync and therefore new Mailing List in Zoho Campaigns. I'm sure that I haven't reached the day limit of syncs. I want to fetch the data only once. So far it was going smoothly. Could you help me with that?
All the best & thanks in advance, 
Ania