On initial load they are present, but when u use the app for a while they disappear....

The issue was introduced with an update of angular material. Rolling back to 1.1.10 helps for the moment but we should get in touch with the material guys. The issue was introduced with https://github.com/angular/material/commit/47527f245acc8382a69a42a07989fd5f646e9744
Fixed in https://github.com/dzhw/material/commit/c8582ea259695e5b4719d0c6e73b3294994bb6c9, waiting for merge. (ref. https://github.com/angular/material/issues/11603)