Heroku. MariaDB. Access denied for user

I'm creating new app on Heroku. Installed add-on "JawsDB Maria" successfully - I can open it's dashboard

In PHP on connection to DB I receive error:

SQLSTATE[HY000] [1044] Access denied for user 'vcgu1h273742rn5l'@'%' to database 'jeyx2j66ipgtqe11'

I'm sure that problem is not in PHP, because the same error I receive even on MariaDB dashboard trying to Create New Databite - https://prnt.sc/rj4dr4 .

Looks like solution is to GRANT ALL PRIVILEGES to user. But using dashboard I can't execute even SHOW GRANTS.

Questions:

1. Can somebody help how to solve this problem?
2. Or, at least, which way I can GRANT ALL PRIVILEGES?

I've tried:

• read Heroku docs: JawsDB MySQL, PHP + DB
• searching for similar problems in Heroku support, Google, SO:
• • the best match I found is here. But heroku pg:psql - it's tool only for PostgreSQL.
• tried to find useful command for my case in Heroku CLI Commands

Additional info - I'm sure it is not important, but just in case it is:

• project is based on Yii2
• for easy deployment on Heroku installed "purrweb/yii2-heroku"

I've waited for 8 hours, hoping there is some trigger, that will complete all necessary settings. But it didn't helped.

Then I reinstalled this add-on. And now all works fine! So, that was some kind of "JawsDB Maria" bug.