Unable to allow kernel extensions, but found workaround

[macstatic]

Being new to MacOS 10.13 (I've installed all the OS updates and am at 10.13.6) never could understand how to enable/allow new kernel extensions (KEXTs).

No wonder!!! Because it never actually worked as it should on my system, despite doing a clean install of the OS. What happens is that I get this screen, and nothing at all happens when I press the "Allow" button (I would expect it to go away once pressed):

Then I found and read Nothing happens when I clicking the Allow button on MacOS in the Security and Privacy.
So this is what I did, following those instructions:
1) In the Keyboard system preference, under "Shortcuts" I selected All controls (see bottom left hand side)

2) Next I opened the Security & Privacy system preference.
Now, instead of clicking (with the mouse) on the "Allow" button I press the TAB key multiple times until that button is highlighted.
Once the "Allow" button is highlighted, I press the SPACE-BAR to select it. Now you can finally select those kernel extensions (using the mouse as usual).

But the big question remains: why am I having this problem in the first place?
The linked article says it's because of mouse or trackpad customization tools, but I don't know of having installed anything like that.

 

[KeesMacPro]

why am I having this problem in the first place?

You're coming from a previous OS ,if I remember well Mavericks or El Capitan.
With (almost) every release of a new OS , the system is getting more reluctant to install "unknown/old" software.
SIP started with El Capitan and is a good example of that.
So for e.g. certain advanced options , you can disable SIP, do your thing, and enable SIP afterwards.

Looks like you found the workaround for your kexts

 

[macstatic]

You're right: 10.9 Mavericks first, then upgraded to 10.11 El Capitan before going for 10.13 High Sierra.
Some of the software I installed (shown in the previous screenshot, ready for approval) are newer versions which are specifically made for 10.13 (Little Snitch, Focusrite audio interface driver and DriveDX) while "Siliconimage" (driver for PCIe SATA interface card) isn't and in my experience doesn't work with 10.13 at all. Could one incompatible KEXT be responsible for blocking others?

I've read about the SIP disabling at tried it at some stages as well, but this isn't necessary to do before allowing them (Security & privacy" system preference as in my screenshot earlier), is it?

 

[KeesMacPro]

Could one incompatible KEXT be responsible for blocking others?

No , i don't think so.
But what could happen is that you try to install a couple of kexts at a time, and then it's not visible anymore which one is blocked .... as happened to you.
Might be saver to install one at a time and for some apps I even left security preferences open, to be able to check immediately (during install) if its blocked or not...
Workarounds , be water my friend

Disabling SIP (temporarily) can be necessary to get access to the root of the system, and can be risky too.
I remember installing this way some outdated software and it worked, but the result was kernel panics at sleep/wake ..
So if the only way to install a kext is by disabling SIP , keep in mind this can lead to all kinds of issues.
I just mentioned at as an example of the more and more advanced protection (with its pros and contras) of the Mac OS.

 

[macstatic]

I'm the OP and discovered that my own solution posted here doesn't work. I have no idea why, but I just posted another thread with a final solution to the problem with a step-by-step guide.

Basically you just restart the Mac into "Safe mode", click the "Allow" button, then restart into normal mode again. I just can't remember if I had to disable SIP first or not. Does anyone know?
If not, can anyone suggest some software with a KEXT that I can try to install, then easily un-install it afterwards -just so I can try out my procedure?