Hey ​@Silviya_L , thank you for flagging this! We are not aware of this issue.
I tried to replicate it (using the ‘”Lock all” and “Lock background only” features) and everything seems to be working fine on my end.
Is this happening in a specific files or across all files?

Could you try force-quitting and clearing the cache (browser and/or desktop app, depending on where you’re experiencing the issue) to see if that helps?

If the issue persists, please reach out directly to our support team by filling out this form: Submit a bug report
In the form, make sure to:

• Use your Figma email account
• Describe the steps you’ve taken
• Share a short video clip of the issue
• Include the URL of the affected file and grant edit access to support-share@figma.com (you won’t be charged for this)

This will help our support team to investigate the issue more effectively. Thank you!

Hi! I found the same problems. Copying (Ctrl+C + ctrl+v) and duplicating (alt) an element is still possible while it is locked.

Hey ​@Fruh , 
This is an intended behaviour. For example, if you lock a specific section, you should still be able to copy and paste this section.

As a reminder, 

• Lock all is to prevent the section selected and its contents from being moved or edited
• Lock background only is to prevent the section selected from being moved or deleted while its content is still editable

Hope this clarifies!