In a recent troubleshoot with a customer it came to light that password change message would occur and a broken form would be shown to the user. After some troubleshooting it came to light that the next gen UI would be enabled and password change options aren’t fully feature parity yet. The at logon would allow you to change but not always work, and after logging in and looking for a change password option that wouldn’t be there. All the other options in StoreFront itself would be correct.
Solution for the customer was a revert to the original unified experience current gen StoreFront look and feel.
For a reference take a look at: https://docs.citrix.com/en-us/storefront/current-release/whats-new
Hope it helps