Why is the mask tool not working?

[joey_hello]

Why is the mask tool not working? I applied a gray mask to the areas that needed to be covered and then used the stamp tool, but there are still patterns in the gray areas that haven’t been protected，i using iPad os18.4 nomad2.1

[joey_hello]

[stephomi]

[joey_hello]

Thank you! It worked. I spent three days searching through the Chinese internet but couldn’t find the answer. I didn’t expect it to be solved so quickly. Thanks a lot!