Filtering in mixed flat view not always correct

I've noticed a strange behaviour with filtering files and folders in mixed flat view.
For example, the following file structure:

Test folder Test folder 1 Test folder 11 Test file 111.txt Test folder 12 Test file 11.txt Test folder 2 Test file 1.txt

Mixed flat view inside Test folder:

Test folder 1 Test folder 2 Test folder 1\Test folder 11 Test folder 1\Test folder 12 Test file 1.txt Test folder 1\Test file 11.txt Test folder 1\Test folder 11\Test file 111.txt

If I initiate filter (shift *)
"2"

Test folder 11 Test folder 1 Test folder 12 Test folder 2 Test file 2.txt
As expected.

If I turn on "Filter folders in Flat view"
"2"

Test folder 2 Test file 2.txt
I'd expect Test folder 12 to be displayed.

"11"

	<empty list>

It looks like if "Filter folders in Flat view" is on, only first level folders and files are displayed.

That may be considered as a specific implementation and not a bug. However, if I filter with NOT filter (start with ~), everything works as expected.

Test folder 12 is below Test folder 1, which doesn't have a "2" in it and is being filtered out.

Thank for so quick reply!
Probably, it's as expected. In the Grouped view it's definitely right.
However, there is a question. I have a large folders/sub-folders structure. I set mixed mode and want to filter them by name. And I can't. I still can select by mask, but not filter. Am I missing some functionality?

Tools > Find Files may be better for this scenario than Flat View + folder filtering.

Thanks, DO is very powerful, I can definitely filter/search in many way.
I see my question is not a bug report, but a suggestion to improve.
I feel folder filtering can be improved. Currently, files filtering in flat view is much more functional due to filtering ignores their location.
That would be great to have the same for folders in mixed flat view. Just feature suggestion.

+1