Issue with Mathpix-snipping-tool on RHEL8

I went step by step throughout the instruction placed under the following link:

However the app is not working as expected after clicking select I can see the whole screen as black and particular selection results also with black image. When I run from cmdline the following errors are shown:

(mathpix-snipping-tool:28027): Gtk-WARNING **: Unable to locate theme engine in module_path: “pixmap”,
Gtk-Message: Failed to load module “pk-gtk-module”
Qt: Session management error: None of the authentication protocols specified are supported.

Although could be lunched from GUI without errors.

Checked the mentioned module and it is installed:

$ rpm -ql PackageKit-gtk3-module-1.1.12-4.el8.x86_64

$ dnf info PackageKit-gtk3-module

Installed Packages
Name : PackageKit-gtk3-module
Version : 1.1.12
Release : 4.el8
Architecture : x86_64
Size : 27 k
Source : PackageKit-1.1.12-4.el8.src.rpm
Repository : @System
From repo : AppStream
Summary : Install fonts automatically using PackageKit
License : GPLv2+ and LGPLv2+
Description : The PackageKit GTK3+ module allows any Pango application to install
: fonts from configured repositories using PackageKit.