"Edit files" dialog doesn't remember its settings

Summary:

Using "Edit files" for custom imported project resets its filter settings on each opening.

Steps to reproduce:

1. Click New Project
2. Choose Import Project -> Import Existing Project
3. Load a custom project, i.e. with empty main.cpp and empty makefile.mk.
4. Click in the Projects pane on the project name, then "Edit files"
5. In the field "Show files matching" add "*.mk" and click "Apply filter"
6. Check the makefile.mk and click "Ok"
7. In a file explorer add makefile2.mk to your project directory.
8. Open "Edit files" again

Expected result:

"Edit files" should have the same filter as last used in this project.

Actual result:

"Edit files" filters have been reset to default ones and require adding "*.mk" manually again.