The new Gutenberg block editor has some permalink issues as described below.
When you first create a post and are working on it, under the Settings > Document controls, you won’t see any permalink option.
If you press the Save Draft option at the top as you are just starting out with your post, then a permalink will be created and you should have an option to edit it.
Some screen shots are below to illustrate the problem. There are some scenarios where a post is created, but a numerical permalink will be generated.
In the Test 2 example below, you can see the problem with no ability to edit the permalink even after the draft has been saved.
In the example below, after additional text has been written and some time has elapsed, the ability to edit the permalink URL is showing up.