Zoho Invoice <-> Zoho CRM syncing

Zoho Invoice <-> Zoho CRM syncing

I'm having a problem that I can't figure out.

We are using Zoho Invoice for a while now and have about 85 accounts in it with contacts and invoices. Now we are setting up Zoho CRM.

So originally, we had clients' names as Display Name in Zoho Invoice. When we synced data with Zoho CRM, new accounts were created, but account names were client names and we wanted them to be Company Names. Everything else was fine, invoices were showing in proper accounts etc.

So I deleted everything from Zoho CRM, emptied the Recycle Bin, changed (manually) all Display Names in Invoice to Company Names, all with hope that these Accounts will be synced again, this time with a proper Company Name as Account Name.

Unfortunately, it didn't work out. It seems like Zoho CRM still "remembers" that it already synced the data (accounts, contacts, invoices), and is ignoring those, updating just newly created ones.

So my question is, how do I restore these old contacts, something like wipe the CRM clean or make it "forget" that it synced those entries already and "force" it to do them again?

Thanks,!