Local adjustment settings not remembered

New attempt:

I repeated the LR deinstallation (via Cloud App) and reinstallation -
this time REMOVING all settings + plugin information and starting with an empty Preferences folder.

The problem stayed the same.

Here is another "protocol" of what I did after the clean reinstall:

Apply masks and observe:

0.  Before starting first gradient,
     uncheck "Reset sliders automatically" ...

     Preset GUI shows "Custom" and Exposure = +1.00

1.  Select Temp, adjust from initial 25 to 10
     (via slider after maximally expanding right Develop panel)
     -> GUI shows "Custom" and Temp +10

     draw 1st gradient

2.  Exit Masking

Now, this entry in Lightroom Classic CC 7 Preferences.agprefs has changed:
from   AgDevelop_localizedTemperatureLast = 0.25,
to        AgDevelop_localizedTemperatureLast = 0.23982,

Activating Masking again, it still shows "Custom" and Temp +10

3.  For a 2nd gradient (after pressing M for the 2nd time)
     change to Tint, change to -20 (via slider)
     -> GUI shows it shows "Custom" and Tint -20

    draw 2nd gradient

Without exiting Masking, we see the same change for Tint
from   AgDevelop_localizedTintLast = 0.25,
to        AgDevelop_localizedTintLast = 0.23982,

Saving may show some delay, but we need not exit Masking to see changes in agprefs.

Exiting and Activating Masking again, it still shows "Custom" and Tint -20

4.  For a 4th gradient:

    Toggle back to Temp -> it now shows 24 (not  10)
    Toggle back to Tint -> it now shows 24 (not -20)

    Now, we change back to Temp and change it from 24 to 10 by typing it in
    (not via the slider) !!!

    This change changes AgDevelop_localizedTemperatureLast to
    AgDevelop_localizedTemperatureLast = 0.01 (not 0.10)

    Toggling Temp/Tint, Temp now shows 1 (not 10)

    Adjusting Tint to -20 by typing it in, we get
    AgDevelop_localizedTintLast = -0.02 (not -0.20)

    Toggle back to Temp -> it now shows  1 (not  10)
    Toggle back to Tint -> it now shows -2 (not -20)

Summary from these examples:

a)  Changing values by sliders, stored values change by a small amount.
b)  Changing values by typing them in, stored values are 10% of the entered value.

I still hope that someone can reproduce / understand my problem.

PS  attached are the agprefs files (added .txt suffix) from clean reinstallation and after the steps above