replace_string doesn't work when string to replace contains parens

[flysand7]

The replace_string function doesn't seem to be working when the string to replace contains parens. In the example below I'm trying to clear the substring (NoData) from the value of a specific JSON field. If, instead, I try to clear just the text inside the parens (i.e. NoData), then UQL returns the expected json value, which leads me to believe the parens are at fault here.

The failing case occurs on the following JSON:

{"alert_state": "Normal (NoData)"}

With the following UQL query:

parse-json
| extend "alert_state"=replace_string("alert_state", ' (NoData)', '')

The query returns the same JSON that was passed in, suggesting that nothing has changed about the alert_state string.