Autocomplete HTML5 Viewer 2.12.1

Hi,

 

We have recently noticed an odd behavior with the default Query Tool > Autocomplete box in HTML5 viewer. Any Map Service from our ArcGIS Server 10.6.1 haveing layers with long field names e.g - ABCD_FIRE_EVACUATION_ZONE_1, shows an error message on top of the query panel -

 

An unknown error has occurred.

 

Upon checking the issue in the Browser console it shows as a javascript error.

 

>> TypeError: Cannot read property 'label' of undefined

 

We have tried all possible options to fix this issue by recreating the map service or reinstalling the essentials and the html5 viewer, but all options fail. 

 

The same map service query works fine perfect from ArcGIS Server REST Query interface. But the HTML 5 Viewer Query tool Autocomplete box doesnt work at all for long field names in any of our map services.

 

 

Thanks,