My status screen holds its breath whenever the log rotates

The displayed timestamp stops as well, then jumps ahead with no readings shown for the gap.

That leaves two possibilities in my head: missing samples or samples waiting somewhere, can you see whether the file has them?

Did those timings show anything? I ask because rotation was when our report tool copied the previous file to a slow share.

Found a copy-to-archive call in the rotation handler, it sits on the same loop as the reads and the delay matches the freeze... I hadn't realised that archive folder was remote.

That's promising, ours recovered once archiving stopped holding up acquisition, though we still had to show when the archive was behind.

Does your proposed background writer have a bounded queue and an explicit overflow policy? Moving the wait can otherwise turn a visible stall into silent memory growth, which is a pain to hand over.

I've moved archival copies off the sampling loop and capped the pending work, failed copies stay local with an alert; a deliberately unavailable share no longer freezes the viewer, and the sampler timings stay steady.

Good, the unavailable-share test is the bit I wanted to hear about, our first fix worked only while everything was behaving.