I have had this problem for a few months now and despite multiple remote sessions/calls/email with zoho support it has not been resolved, I'm really hoping someone can help me out.
All of our emails sent/received to contacts
are not automatically syncing with the deal associated to the contact. This happens even though the contact is the 'main' contact for the deal (linked via the contact lookup field), even after a few days pass (not an issue with delayed synching), and even after emails are sent/received after the deal is created and the contact is linked. IMAP seems to be working fine as the emails sync with the contact record.
On the example below, the deal is linked to the contact receiving/sending emails, but no emails are shown under 'emails associated with this deal'

But when changing the drop-down box to 'emails associated with this contact' one can see the emails

Similarly, the emails are visible on the contact's record.
According to this:
Email Association With Deal - Online Help - Zoho CRM - Zoho CRM should be automatically linking these emails to the deal as they fulfill all the criteria to be automatically linked.
Of course I know I can manually link these emails to the deal, but this is not feasible and does not ensure future emails between the contact will be linked to the deal, anyway (correct?)
Please can someone assist me with this, I am going a bit insane and the support team have made zero progress trying to fix this, their last response was that the emails were sent before the deal was created, which isn't true for any of my deals so not sure they are really trying to solve this.
Thank you so much in advance