I am using Katalon version 6.3.1 and Ubuntu, even though the problem I will mention was noticed in Windows as well.
Here is the description of the problems I found with the interface:
Whenever I create a new Object (Web Services Request) and go to the Authentication tab, choose Type=OAuth 2.0 fill in information I need and save the file, when I try to open it again, the Authentication tab is back to its original state and all information I “saved” is lost, going back to this screen:
Besides that, there is the option of hiding the password but it is not working, see images with both ‘true’ and ‘false’ options:
Also, there is a bug when choosing the option “Password Credentials” for the Grant Type.
When I choose it for the first time in the drop-down box, the username and password should be editable but are not.
To do a workaround for that, I go to the drop-down box, select another option, e.g. “Authorization Code” and then click again in “Password Credentials” in order for the fields to become editable.