What you watched your attorney do is a good example of what the strategy guide calls "maintaining investor trust through reporting and transparency." He communicated a loss honestly, personally, and in a way that made each investor feel like a specific person rather than a line on a distribution list. Three re-ups after a 1.09x return says the communication did real work.
The BCC moment you described is worth sitting with. Nine people received the same two sentences about a deal that fell apart. From their side, they had no way to know whether you were thinking about their money specifically or managing a mailing list. That uncertainty is what silence after a difficult update usually means. It does not mean they are gone, just that the communication did not build anything.
A practical difference to consider: your attorney wrote one paragraph per person, referencing something specific from the hold period. That specificity is the thing that made it feel like a relationship rather than an obligation. You do not need to write like him to get part of that effect. Even a short note that names something you actually know about a specific investor, what they told you they were hoping for, what their timeline was, can shift how the message lands.
One thing worth knowing: how you raise capital and how you communicate with investors once they are in a deal has real legal structure around it. Securities law governs what you can say, to whom, and when. I would ask a securities attorney before changing how you communicate with current or prospective investors, so the improvements you make are also compliant ones.
What did you know about those nine investors individually before you sent that update? That would help me give you something more specific to think about.