Product details removed during update from other system

Product details removed during update from other system

We maintain our product details in an other system. These details are synchronized with Zoho at the end of each day, through an API. This has worked perfectly sofar. But last Monday, all product codes and some other product data have been wiped during the synchronization.

We are still in an implementation phase, so it is not a disaster. 

Oddly, some fields that have been wiped, don't exist in the other system and can't have been touched by the API. It is almost like something has triggered an automation which has cleared certain fields for all product that were part of the sync. (obsolete products that still existed in Zoho at the time were not affected).

So the sync must have been the cause, but the API couldn't have done it by itself.

Is there any mechanism in Zoho that could cause such a thing?
Like : If field X is set to value Y in the API, then wipe some selected fields.

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