Recently I had a mental blackout and updated my LG´s Web OS and Firmware to Version:
13.30.56.01 webOS Version 8.3.0-2301
Now the only way to access "SM WB" is to enter the "Power-Only Mode". In this mode you cant´t connect via "DeviceControl" to the TV, switching back to the "Usermode" Loads initial Settings which is annoying, but okay.
I tested this just briefly, but it seems that LUT upload has no effect, I even got once a very strange behaviour, were the TV displayed the LG home screen and the menu's but no video content via HDMI nor on YouTube (UI was visible).
Is there another way to upload a LUT to the TV, or to confirm if it is uploading?
The measurements seem to show, that there´s no change after uploading the LUT.
Is there a way to rollback this update?

Thanks for any tips and support!

You may want to email Ted directly at his displaycalibrations.com website, as I think he has the responsibility for DeviceControl support. This forum is aimed at ColourSpace support.
Generally, TVs don't give you the ability to roll back firmware.

Please don't use the power-only method; ignore it.

Entering the SM WB menu is not required with LG 2023 OS LGs because the TV uses the SM WB and regular WB adjustments to calculate the factory calibration 1D LUT.

It's not working like this with 2022 or older TVs.

So you can use the regular menu to fix RGB balance; just use the Warm +50, which will have 192 in RED in SM WB, and change only the B/G channels to fix 109% White (to positive or negative direction)

Each picture mode stores its color temperature settings, so you can use the same method to pre-cal HDR10 or DoVi.

Thanks for your help, LUT upload now is working again after a unplugged the TV for some time!