I don't know where I can report a bug to Toolset, so I report here.
I want to create a custom post type named "Social Media", as "media" is the singular and plural form, so I type the same in both Name plural (required) and Name singular (required). when I save it, the post type doesn't be saved but no error message prompt and then reset the setting I did.
I can only do it to type the plural form with different name and save, then change back the plural form name.
If I try to create a post type with the same singular and plural names I get a pop-up message saying it is not recommended, and then a warning with a checkbox that I must mark to ignore the warning, as you can see in my screenshot.
I don't have any other info about your site to know which version you are using or what other plugins you have installed that could somehow have prevented you seeing these warnings, but it is not a reproducible bug with the current Types version.