Hi,

Though, any REGEX function with "Positive Lookbehind and Positive Lookahead" feature can be tested in TEST environment in Preprocessing Frontend but after the ITEM is updated, the state of the STATUS field turns to "UNSUPPORTED" and at the INFO field, a red exclamation mark appears. If you click that red icon a pop-up field appears as below; 

I've tried many "Positive Lookbehind and Positive Lookahead" features but couldn't have succeeded. 

Eg: (?<=myip\.opendns\.com\nAddress:  )([\d\.]+)

Instead, the below REGEX function is supported as below; 

Is this a bug or "Positive Lookbehind and Positive Lookahead" regex features are not supported in ITEM Preprocessing.

Regards,
Nuri.