Las máscaras de cielo y sujeto no funcionan

In a next step you should try to switch off the GPU support from the Lightroom preferences and check if that helps to fix the issue.

Go to Lightroom > Preferences > Performance tab > Uncheck "Use Graphics Processor" > Restart Lightroom.

https://helpx.adobe.com/lightroom-classic/kb/troubleshoot-gpu.html

You should also try the suggestions in the section "Solution 3..." and "Solution 4..." (here especially point 6) in the linked document above.

What has been changed on your system before the error occur?

Please provide also a copy of your 'System Info'. This can be get from the LrC Help > System Info menu item. There's a copy button in the System Info dialog. Press this button and paste the info into your next forum post.

In a first step please try resetting the preferences of Lightroom Classic:   https://helpx.adobe.com/lightroom-classic/help/setting-preferences-lightroom.html

It's recommended to backup your preferences before you reset the preferences to the default settings: 

https://helpx.adobe.com/lightroom-classic/kb/preference-file-and-other-file-locations.html

What has been changed on your system before the error occur?

Which operating system do you use?

Which version of Lightroom do you use?

Please post the exact version and not only phrases as "recent", "latest" and so on.

Do you get an error message? If yes, please post the exact message or an screenshot.