views exposed filter does not use enabled ajax

how do i get the ajax feature to work with exposed filters? am i missing configuration options? what do i need to check?

• i am using drupal 8.6.1 and a couple of views extensions (better exposed filters, draggableViews, viewsargordersort, views bulk operations, views field view, views geojson and views tree item); i have a running site with other modules enabled
• i created a simple page view with standard settings and a content type exposed filter (see screenshot attached)
• i enabled ajax under 'advanced settings'
• issue: a click on the apply button causes a page refresh. the filters are working correctly, though. it seems as if enabling the ajax setting has no effect whatsoever

i unsuccessfully tried:

• selecting better exposed filters for the particular view
• checking if scripts/templates/hooks override settings or similar
• checking the browser console for suspicious output (nothing)