I just created another Blender Scene with an simpler world node setup.

Open the Scene
Click the Viewport render icon.
Change the strength in the Background node in the shading tab.
In the properties Tab switch from Studio_052 to Studio_053.
Change the strength in the Background node in the shading tab. Nothing happens. Cycles is not updating.

I tried it also on another computer with fresh user settings and reseted to factory defaults. The problem is still there.
It is strange, the viewport update works if Studio_052 is set as World, but if you switch to Studio_053 as World the viewport update isn´t working.
There is only an update once in Studio_053 World when you switch from Studio_052 to it. But once Studio_053 is set, changing for example the strength or rotating in the Mapping Node, has no effect at all.
I tried as described above.

Open the Scene World_HDR.blend
Click the Viewport render icon.
Change the strength in the Background node in the shading tab to 0. The Viewport rendering is updated.
In the properties World tab switch from Studio_052 to Studio_053. The Viewport rendering is updated.
Now change the strength in the Background node in the Shader Editor to 0. Nothing happens. Cycles is not updating.
In the properties World tab switch from Studio_053 to Studio_052 and back to Studio_053. Now the Viewport shows the correct result.
Now you can try to change the strength in the Background node in the Shader Editor to 1. No Viewport Update. Try to Z-rotate in the mapping node. No Update.

I tested yet another file.

It seems that only one World is working correctly. When switching to another World and trying to adjust Parameters there is no cycles viewport update.

Open Blender Scene.
Activate Viewport rendering

Change the Background_Strength in the Sky_Sun_Control node in the Shader Editor to 0. The Viewport rendering is updated.
In the properties World tab switch from Sky_001 to Sky_002. The Viewport rendering is updated.
Change the Background_Strength in the Sky_Sun_Control node in the Shader Editor to 0. The Viewport rendering isn´t updated.

Only changes in Sky_001 World is updated in the viewport!