Magento 2 – New storeview redirects back to default store view

I created a new storeview accessible under the URL app.example.com

I added this to the .htaccess to set the MAGE_RUN_CODE Environment Variable to app if the URL app.example.com is called:

SetEnv MAGE_RUN_TYPE store
SetEnvIf Host ^example.com MAGE_RUN_CODE=default
SetEnvIf Host ^www.example.com MAGE_RUN_CODE=default

SetEnvIf Host ^app.example.com MAGE_RUN_CODE=app
SetEnvIf Host ^www.app.example.com MAGE_RUN_CODE=app

Then I changed the base url of my new store view to http://app.example.com/

Problem:

I created a new CMS page for the new storeview with the URL Key app-test.
But if I try to access it via app.example.com/app-test, then I get redirected to https://www.example.com/catalogsearch/result/?q=app+test

I tried to reindex and flush cache, but it made no difference.