I have the latest fire brigade installed on a 6.4.1 SHC (and the appropriate TA on the indexers). I'm getting the following errors from "cumulatize usage over all hosts panel" in the the cross-host index overview page.
[subsearch]: Failed to fetch REST endpoint uri=https://127.0.0.1:8089/services/data/indexes/dh_clocksync?count=0&search=disabled%3D0 from server=https://127.0.0.1:8089
[subsearch]: Unexpected status for to fetch REST endpoint uri=https://127.0.0.1:8089/services/data/indexes/dh_clocksync?count=0&search=disabled%3D0 from server=https://127.0.0.1:8089 - Not Found
To elaborate on my answer a bit more: Those pages will attempt a REST query to find out about the configured retention limits for the index. The purpose is to be able to report "% of capacity" as compared to current usage. The SH will attempt to do this across all hosts, including itself. If the index definition for dh_clocksync only exists on the indexers, the SH (127.0.0.1) will report the error you see.
You might consider the Troubleshooting menu, the "Troubleshooting Index Configuration" to see which host(s) don't have that index.
What answer/insight are you looking for? I ask because it might be available in the DMC now (and if not, we can let the DMC team know). I have DMC bias...
Psst: I think you mean Fire Brigade, not Fire Bridge.