Can’t find this case on line, but it’s a nice read on Westlaw or Lexis. The court in Paice, LLC v. Hyundai Motor Co., 2014 WL 3773666 (D. Md. July 29, 2014) held that the parties’ negotiated bar did not cover the later-enacted IPR proceedings.
My article (link a few posts below) talks about this issue in detail, and the need to pay attention to both sides of this issue: is your client protected because the bar applies to IPR, and are you complying with the bar by not participating, or going ahead and doing so, in IPR. Traps on both sides.