"Attach a file" button doesn't open GtkFileChooserDialog in Tag editing page

Summary

In Tag editing page, nothing happens when the "Attach a file" button is pressed.

I'm sure that I could attach a file to released tags in Jan 10, 2019. I confirmed this issue happens with various browsers listed below. But I'm not sure whether this could be related to LinuxOS environments or not, sorry.

Steps to reproduce

• Open released Tag editing page.
• Push (Press) "Attach a file" button.

My env:

• OS: Ubuntu 18.10 and Ubuntu 19.04
• Gnome-shell or Budgie desktop session (Gtk+-3).
• Browsers: Chromium, Google Chrome, Firefox and Epiphany.

Example Project

My GitLab project's Tags: https://gitlab.com/tista500/plata-theme/tags

What is the current bug behavior?

"Attach a file" button doesn't work in Tag editing page.

What is the expected correct behavior?

Open GtkFileChooserDialog if Gtk+-2/3 desktop session runs on LinuxOS.

Relevant logs and/or screenshots

N/A

Output of checks

Results of GitLab environment info

Results of GitLab application Check

Possible fixes