I have a number of custom functions which have been produced by a range of Zoho Alliance Partners and one by Zoho itself. 

The functions work well 97% of the time. However, I experience 3 or 4 instances a day where an app will fail on the basis of " Error evaluating MAP expression" (according to the Zoho CRM log). To me this appears to be a backend Zoho issue, as the coding is correct, as evidenced by the fact that the workflows work well in the vast majority of instances. 

Is there anything that could be causing this? The failures are causing me real problems. How can I get this addressed?

I hope someone can enlighten me!

Kind regards

Tim