Subpack changes no longer apply if the resource pack is already activated

I do not know the exact game version that introduces this issue, but in the 1.21.120.24 Preview I noticed subpack changes no longer apply if the pack is already activated.

I extensively tested this in Settings → Global Resources with multiple resource packs that make use of different subpacks (including marketplace ones)

Steps to re-produce / Bug information:
- Have a pack with subpacks, you should be fully aware of the subpack’s impact (so you confirm whether the changes are applied or not)
- Activate it in global resources. Note: setting a subpack resolution here where the pack is being activated for the first time WILL work correctly
- However, if you return to main menu (i.e. save the changes) and come back to global resources to change the subpack resolution, it will no longer save, ever

Note: there was another old bug affecting subpacks that made it so the user has to return to main menu once and apply the subpack changes again (twice) before it saves definitely, however this bug is different than: Mojira - Issue MCPE-162002
- No matter how many times you change the subpack and return to the main menu to save, subpack changes never save.
- Workaround: You must deactivate the pack entirely, save, and make sure you set the pack to the desired resolution/subpack on the very first attempt of saving, otherwise there is no other way to save subpack changes!

Note:
Another visual cue that makes this bug extremely obvious is the loading times, now when you change subpacks after the pack is activated, the changes seemingly “load“ or take place instantly, i.e. load times are close to 0, as in the game glosses over it.
As someone who uses subpacks of packs very regularly, I could tell something feels off just from the menu, the loading times were non-existent, which was another sign subpack changes aren’t being saved whatsoever.
Previously it would take 1-2 seconds when your changes are being successfully saved, which was a sign something is being loaded in properly.

Expected behavior:

Subpack changes must apply the very first time user changes them, whether it is in global resources, world resources, or whether the pack is activated the first time or is already active, use of subpacks which is an officially documented feature should not be convoluted for the end user.

Resource pack authors must not have to put up tens of lines of workaround guides for users because now because using subpacks is now ever more confusing.

Note:
This issue might impact all platforms, however I was only able to test on Windows, if anyone has more information, please add.