Shortcode with Twenty Twelve doesn't working

What are the doing hyphens in the first block? That definitely won’t work.

Did you enter these shortcodes into the visual editor or the text editor?

Did you copy & paste the shortcodes from somewhere or did you type them in? If they were originally copied in there may be an issue with the characters delete them & type them in manually.

Do you have a test site you can install this on so that I can see the problem?

Check some sites using plugin, also ther shortcode showing just plain text.
https://digitalmoneytalk.com/blog/blog/exness/
https://wicklowgardens.com/index.php/test-2/
https://www.sumeetkataria.com/gallery-page/
https://solotix.com/solotix-services/
https://www.celldekho.com/sony-vaio-flip-13-review-specifications/
https://www.atlantacitymix.com/2014/03/09/krave/?utm_source=rss&utm_medium=rss&utm_campaign=krave

Can’t be all deactivated/deleted plugin.

Did you enter these shortcodes into the visual editor or the text editor?

Text editor.

Did you copy & paste the shortcodes from somewhere or did you type them in?

Copied, removed formating.

Do you have a test site you can install this on so that I can see the problem?

Up, you can see examples of sites that using this plugin.
You can find many on google.

Maybe, they deactivated plugin, but it’s too many of them, to believe in that.

I’m not sure whether you are looking to argue or are genuinely requesting help.

The plugin does work and when people have problems and ask for help by posting in the support forum they can get help in getting it to work once I can see their site and work out what the issue is.

Taking the first site as an example, when you view the source of the page you can see that the site owner has added the shortcode incorrectly as it shows as:
[tabby title="Company Information"]
rather than
[tabby title="Company Information"]

which would be shown if the shortcode was added correctly but was not being processed.

It looks like they have copied the shortcode text from somewhere and not corrected it. This is a very common error which is very easy to fix and this can happen with ANY plugin that uses shortcodes. It is not something that indicates an problem with the plugin or its code.

Perhaps you have made the same mistake as the owner of that site?

To be more weird, if I copy your example from plugins page, it works.
This works.

[tabby title="First Tab"]
Tabby ipsum dolor sit amet, kitty sunbathe dolor, feed me.

[tabby title="Second Tab"]
Lay down in your way catnip stuck in a tree, sunbathe kittens.

[tabby title="Third Tab"]
sleep in the sink climb the curtains attack, give me fish.
[tabbyending]

Ok, I found the reason, why this is happening.

When you adding shortcode [tabby… there is space betwen “[” and “t”.

So, everyone who experience this problem in future, go between [ and t and press backspace once, it will delete “ghost space”, and your tabs will work.

The best way to prevent this from happening is to not copy & paste shortcodes from a web page but type them directly.

It seems that you may have copied an example that had zero-width-space characters inside the square brackets to prevent the shortcode being processed on that site.