Under the 'config > lovelace' directory create a new directory for the dashboard defined above. In there you should create a folder called ‘dashboard’.
In the dashboard directory put the yaml file that defines the dashboard - in this case ‘ui-lovelace-mobile.yaml’.
Inside the ui-lovelace-mobile.yaml you can define the pages, title, icons etc etc
I used a sub-directory under the dashboard called views and have each page of my dashboard as a single yaml file. Easier to edit and keep stuff together.
The file will also need to specify where the UI-Minimalist custom cards templates are.
Sorry - not much more I can say. I dropped UI-Minimalist for Mushroom TBH.
Originally I had a web/tablet dashboard that ran in the config/ui_lovelace_minimalist folder that got setup by default when it was installed - over-writing the one it created. I added a new mobile dashboard based on the stuff above later.
With the new sections capabilities, I’ve removed both and just use Mushroom cards and sections via the UI to achieve the same results.
UPDATE:
I think that showing the Overview dashboard means it can’t find the actual yaml files for the dashboard, so it’s falling back to the default view. Check your paths/spelling perhaps?
Just remove ui-lovelace.yaml and paste this to configuration.yaml and restart, if the dashboards.yaml in lovelace folder, then filename lovelace/dasboards.yaml