You imported the root, reloaded the page — and the browser still says ERR_CERT_AUTHORITY_INVALID. Before doubting the import, do the boring thing: restart the browser fully. The trust store is read at start, and a reload does not re-read it.
Still warning after a real restart? Check the two classic traps from the last frame: wrong store (Enterprise Trust is never consulted) and wrong certificate (you imported the issuing CA, not the root — verify that subject equals issuer on what you imported).
One more thing that is not a fault: the serving certificate changes on every process restart. By design — the service key is generated fresh per certificate and lives only in process memory, so a restarted process has nothing to reuse. It is also not why the browser warns: the root is stable, and trusting it once covers every future certificate this deployment serves.
Now I can get to a green padlock — and say why a changing leaf certificate is fine.