HTMLView failing to update (occasionally)

A few times now I've had an existing HTMLView window failing to update, but without any errors in the np-out or np-error logs.

More detail: I've had either Dashboard or Project List window open. I've hit update on the window, and all my usual debug logging shows the expected work, up to and including the usual messages about finding the existing window and calling await HTMLView.showWindowWithOptions(). This call seems to return a valid object, as I can read the .customID and .id from it.

The copy of the HTML that I additionally persist to disk is fine.

But the HTMLView does not update at all, instead just stays the same.

This feels related to the as-yet-unidentified-cause of the missing requiredFiles file that occasionally drops .css files. (Reported in ⁠Occasional loss of a Required File)