When I mouse-over the raid lockout display in SavedInstances for the new raid, it say "Boss kill information is missing for this lockout. This is a Blizzard bug affecting certain old raids.".

Reloading UI seems to temporarily fix it, until I kill a new boss?

Which version of SavedInstances are you using?

9.1.2-3-g629ce65

Was it working in a previous version? If yes, which was the last good one?

Appears to work with version 9.1.2-2-ga9bcb7e.
Or I can't tell now since I've reloaded my UI since downgrading and upgrading a few times.

I tried to reproduce but failed. Might need more data to found the source of the issue.

I tried to pug the raid on normal on my hunter but never got into any groups that I signed up for, so I gave up. And now there's new things to do, not much time to try and pug normal Sanctum on even my main. :(

Let's wait 'til next week and see if this can be reproduced in Sepulcher of the First Ones, then we can get more data to fix this.

Aye, I will do a /dump of the lockout in the new raid, should it happen for that raid as well.

I just did a run on normal and it seemed normal up to and during the fight against Soulrender Dormazain. Something might happen that affects the tooltip, when the cutscene of when Garrosh breaks out of his chains and kills the boss?

Is this not fixable, or why has nobody replied to this ticket yet?

Dump: value="[Sanctum of Domination]"
[1]="|cffff8000|Hinstancelock:Player-60-06570EC1:2450:16:359|h[Sanctum of Domination]|h|r"

Its ok! Real life comes first! Theres my /dump

Having the same problem.

Might need more investigation on this. If your lockout is missing boss info on tooltip, please try following steps:

1. Click your DifficultyString like "6/10" in SI's tooltip, then it will be a link in your chat input
2. Add a pair of quotes and /dump to the very head, it will be like /dump "[Sanctum of Domination]"
3. Press Enter and post what you get here

And sorry for late reply, quite busy in recent months.

Thank you for finally responding.

It seemed to me to be quite random, and I don't regularly raid anymore this patch. We'll see if I can pug a normal on my hunter tonight or something.

Error occured in the new raid as well. Unsure if you want a new issue but leaving it here as was asked.
This is normal dump:
Dump: value=[Sepulcher of the First Ones]
Dump: ERROR: [string "return |Hinstancelock:Player-60-06570EC1:2481:14:1467..."]:1: unexpected symbol near '|'

Heroic Dump:
Dump: value=[Sepulcher of the First Ones]
Dump: ERROR: [string "return ..."]:1: unexpected symbol near '|'