Isaiah 26:19
Is anyone able to tell me why the NIV2011 adds “LORD” (i.e. יהוה) to the first clause of Isaiah 26:19?
No other English versions do. Including the NIV84.
There’s no textual issue recorded in BHS.
Oswalt doesn’t mention any other textual issues.
Strange!

I believe I have answered my own question.
The issue is not a textual one – but an interpretive one.
Oswalt (p486) has a discussion about the difficulty of determining the speaker in v19. The possibilities are: the people themselves, God, or Isaiah.
The NIV committee seemed to have added YHWH to make clear their interpretation that this verse is being spoken by the prophet.
I think you’re right. The NET bible has this comment: “At this point the Lord (or prophet) gives the people an encouraging oracle.” The NIV is just trying to be helpful!