Not sure of a fix, but it is possible to bug this invasion.
Currently stuck at 96% of stage 1 in Legion remix today... sat inside and outside it waiting for it to "fix" itself, but look like its stuck this way till the next reset.
WoW Zone
Invasion Point: Val
Shadowlands - Level 45-45.
Details
Counts are what the current game build's data holds for this zone.
The highest voted Wowhead comments for this page. They are community notes, not TheWoWDB comments.
Just stood by the braziers and not only you're fine but your health is regenerating.
Also second phase of this invasion point is awesome as Frost Mage. You're thawing out the NPCs from the ice, and the animation used for it is that of your artifact weapon which in frost mage case, yes, you guessed right, is looking like you're trying to freeze them even more :-D
I cannot beat.
Final Stage – Change in Leadership
Kill the Legion's commander on Val.
Map

The in-game map of Invasion Point: Val.
Community notes from Wowhead · 7 comments
Top 3 shown aboveThe comments below were written by Wowhead users. They are community notes, not TheWoWDB comments. See them in context on Wowhead.
The top 3 are shown in Top Comments above. Read all 7 on Wowhead.