Gaps and buffering 24/96 quality files in Roon Arc while using NordVPN to prevent multiple NAT issues

Did you install the latest update yesterday that fixed some recent gapless issues? (I know you mentioned ARC 138 which would be from this update, but also make sure you updated your Core)

If not, please do and check again. Your issue may be different, but Roon support will surely want you to rule out that is just the known and fixed issue