Lightroom Classic: Adjustment Brush stops working correctly after applying preset

Do you mean that red area? You have turned the mask overlay on, so the brush shows the mask itself in red. Turn it off underneath the image or press the 'O' key.

If that's not what you meant, then please go to 'Help - System Info' and post the first ten lines here. 

Lightroom Classic version: 7.4 [ 1176617 ]
License: Trial
Language setting: en
Operating system: Windows 10 - Home Premium Edition
Version: 10.0.17134
Application architecture: x64
System architecture: x64
Logical processor count: 8
Processor speed: 2.8 GHz
Built-in memory: 16235.9 MB

It's from my home pc, at work pc i have latest Lightroom with licence, but issue is the same

Demo video:
https://youtu.be/sj9wRYpI0Zs
https://www.youtube.com/watch?v=VgGYzL-WjII&feature=youtu.be
It's normal behaviour???