Granafa Alertmanager incorrect GeneratorURL and missing DashboardURL

When we have alerts in grafana alertmanager, they have incorrect Source. Smth like

Source: /graph?g0.expr=rate%28nomad_nomad_job_summary_failed%7Bcluster%21%3D%22staging%22%7D%5B1m%5D%29+%3E+0&g0.tab=1

As far as I understand, tnat comes from default template alerting/templates/default_template.go at main · grafana/alerting · GitHub

where it is taken from GeneratorURL.

Why GeneratorURL is broken and DashboardURL is missing for my alerts? How can I fix it?

Smth like this

Also in alertmanager view of all alerts there is See graph that link to correct url - so I assume alertmanager can generate the correct link