Me neither. It takes a very sharp bend in the flex to affect most ENIG-finished individual component pads, and most larger ground planes/traces are typically not finished (covered with polyimide).
And (again, typically) once the components are soldered in place it is pretty darn hard to bend the flex sharply enough to do any damage. You would have to try really hard. The components would crack before any damage was done to the soldered pads. 
ENIG is one of the most common flex circuit finishes.
Odin
-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Larry Brophy
Sent: Thursday, May 27, 2021 8:04 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG plating Flex Circuit

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Never had a problem with it Victor.

Regards,

Larry

-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Hernandez, Victor G
Sent: Thursday 27 May 2021 14:03
To: [log in to unmask]
Subject: [TN] ENIG plating Flex Circuit

Fellow TechNetters:

   Is ENIG surface plating finish suitable for a flexible circuit in a Rigid
Flex application?   Nickel is brittle.

Victor,