Unable to sync / edit / use zoho contacts with Mac

Unable to sync / edit / use zoho contacts with Mac

hi all, i followed the instructions of adding zoho to the mac's "internet accounts" multiple times now, and although it "worked" i have the following problems:
  1. i cannot edit contacts using the "contacts" app on the mac
  2. i cannot delete contacts using the "contacts" app on the mac
  3. i am unable to copy-paste / move / etc. contacts from icloud to zoho
  4. synchronization is utterly slow (i deleted all zoho contacts from within zoho, no change in contacts)
yes, i am aware this *might* be a mac problem, still this is something that just keeps me from using zoho. so if anyone could provide some help here i would be really grateful, cause this is basically the primary thing that keeps me away right now. (there are like dozens of other small errors in zoho, which is *really* unsettling, but nothing major - THIS is my dealbreaker, at least right now).

cheers!
axel.