Can't stop any apps permission to use data in background

[BeOhBe]

Can't deny ANY apps permission to use data in background!

LG Rebel 4 LTE, Android 8.1.0 (Oreo), Snapdragon, Chrome 91+.

It's my 2nd device, synched with an (almost) exact duplicate, which works fine. My 1st phone has all but 6 apps cut off from using background data. Went to do same to wife's phone and can't!

Everything works Except:
click Settings permission to use data in background on Any app, System or Not, stock or download, gets flag:
"Settings Has Stopped Working."

If "Turn back On" is tried too many times in a row, something balks: and a different flag warning appears.

Data consumption is outrageous with many of the apps I can't deny, and it worries me that some tracker malware might be doing this, but Malwarebytes says phone is clean.

Anyone know what's up with this?
Is there a setting somewhere I've missed?

Thanks in advance..
BeOhBe

 

[B. Diddy]

Does the same thing happen in Safe Mode? https://www.hardreset.info/devices/lg/lg-rebel-4/safe-mode/

 

[BeOhBe]

Ahh, good suggestion. Never tried it, I'll do that n let U kno.

 

[BeOhBe]

B. Diddy,
BTW, The instructions to Safe Mode are wrong. It's:

Hold Power button
At pop-up Hold Power Off
Click Safe Mode
[HOLD is key. There it says Tap, which will turn phone off. ]

Off is Auto at another restart.

 

[B. Diddy]

Thanks for the clarification -- that site sometimes has incorrect or out-of-date steps.

 

[BeOhBe]

Well the update isn't good. D Diddy, the answer is yes, settings still crashes in safe mode every time I click the permission to use data in background off, on every app I've tried.
Just to cover all the bases a second time, I did a deep scan, came clear, turned off/on, cleared Chrome and Google + Google Play Services out of their cache n data, deleted total search history, paired down cookies to only known ones... All to no effect/change. Also tried my own identical phone again, and it lets me cut off bg data no prob.
I'm stumped with no ideas left.
Anyone has any knowledge on this would be much appreciated.
BeOhBe

 

[B. Diddy]

I'm guessing it has to do with a firmware glitch and/or Oreo slowly becoming outdated. Unless someone else has an idea, the next step would be a factory reset. If the problem persists, then I'd recommend looking into upgrading to a phone with a more current Android version. Sorry!

 

[BeOhBe]

B Diddy, Well one thing in this sorry deal is her screen is broken and we're due for a new phone anyway. Thanks for the help, n u never kno, someone may ring in here with a working idea before that.
You'all have a good holiday years ending now.
BeOhBe