If you can provide steps to repro it than it's a bug otherwise it may or may not be a bug.
Take a look at GoFish.app v3.0 Global String Search/Edit/Replace File #9925.

>Hi,
>
>We have trying to replace Message Code in VFP forms using "code references" in VFP8, but we get a replacement error said "Error encountered during Replacement" is that a bug, and some code disappears on command Group.
>
>Is there any other search option can do the job ?.
>
>Best Regards