Is a Defendant's failure to respond to an argument in their opposition to the argument put forward in their opening brief constitute waiver or abandonment?

Plaintiffs do not address this issue in their opposition. (See Doc. No. 33 at 23-24.) By failing to address the issue, which was among the reasons the court dismissed this claim previously, they have waived it. See Stichting Pensioenfonds ABP v. Countrywide Fin. Corp., 802 F. Supp. 2d 1125 (C.D. Cal. 2011) ("[I]n most circumstances, failure to respond in an opposition brief to an argument put forward in an opening brief constitutes waiver or abandonment in regard to the uncontested issue.").