Source links do not work when on same domain as Alertmanager

What did you do?
We have prometheus and alertmanager behind a proxy under /alerts and /prometheus. When an alert fires the "Source" element is set to the url domain.com/prometheus?somequery. It seems that the javascript is intercepting this click before the link is resolved.

What did you expect to see?
Link to the proper prometheus page linked in the

What did you see instead? Under which circumstances?
It seems that the javascript is intercepting this click before the link is resolved, because the page quickly shows a "loading" then back to where it was before. If i edit the DOM and make the domain different from alertmanager the link works.

Environment
Kubernetes, prometheus operator helm chart

• System information:

Chrome Version 73.0.3683.103 (Official Build) (64-bit)

• Alertmanager version:

quay.io/prometheus/alertmanager:v0.16.1

• Prometheus version:

quay.io/prometheus/prometheus:v2.7.1

• Alertmanager configuration file:
  n/a frontend issue

• Prometheus configuration file:
  n/a frontend issue

• Logs:
  n/a

No source file or test is named. Start by reproducing the Source-link behavior with Prometheus and Alertmanager on the same domain, then trace the frontend click handling. Done means the Source link opens the proper Prometheus page instead of briefly showing a loading state and returning to the current page.