Thanks for reporting this! It looks like the trooper page has several stale alerts at the moment, and I would guess it's because the trooper page is still pulling from old trees with the "milo" prefix. 

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/c517a004cb0ec18b3af27a1f79ad11f1c1946902

commit c517a004cb0ec18b3af27a1f79ad11f1c1946902
Author: Tiff Zhang <zhangtiff@google.com>
Date: Mon Jun 26 22:03:57 2017

SoM: Make trooper tree use milo.

Bug:736838
Change-Id: Ic07f8b8012e404a2c64c1ee182c6a35814d82919
Reviewed-on: https://chromium-review.googlesource.com/549008
Reviewed-by: Sean McCullough <seanmccullough@chromium.org>
Commit-Queue: Tiffany Zhang <zhangtiff@chromium.org>

[modify] https://crrev.com/c517a004cb0ec18b3af27a1f79ad11f1c1946902/go/src/infra/appengine/sheriff-o-matic/som/alerts.go
[modify] https://crrev.com/c517a004cb0ec18b3af27a1f79ad11f1c1946902/go/src/infra/appengine/sheriff-o-matic/som/main_test.go
[modify] https://crrev.com/c517a004cb0ec18b3af27a1f79ad11f1c1946902/go/src/infra/appengine/sheriff-o-matic/som/trooper.go

This should be fixed in the next release. (Tomorrow)