Alexa last_called_summary filled in erratically

This is a bit complicated to explain, so bear with me…

Is anyone actually using the “last_called_summary” attribute on alexa media player entities reliably? This supposedly contains the command that was spoken to an echo device, but I am just doing some testing and finding it behaves fairly predictably erratically, if you get my drift…

I am watching in node red for any difference (or lack thereof, so I am seeing everything) between data.event.new_state.attributes.last_called_summary and data.event.old_state.attributes.last_called_summary, and just reporting in debug nodes. What I see is:

Firstly, saying something that Alexa “natively” responds to, such as “alexa what time is it”, if I say

“alexa what time is it” with no pauses, I see a single update with that string in the attribute, and it stays there. If I say

"alexa " - and pause a second - “what time is it”

I see two updates, the first with the attribute set to “alexa” and then with “what time is it”. Slightly odd maybe, but seems consistent.

Now - if I say something that does not elicit a “built-in” response but something that triggers an alexa routine, it’s different.

I have lots of queries I can make to home assistant which are sent from Alexa by using routines triggered by phrases to set a virtual light to a certain brightness which HA then picks up. So for example I can say “alexa is the garage open” and I will get a spoken response “both doors are closed” etc.

If I say “alexa” - pause - “is the garage open”, I see THREE changes in the attribute, firstly set to “alexa”, then “is the garage open”, then immediately null “”.

If I say “alexa is the garage open” with no pauses, I sometimes see two updates with “alexa is the garage open” and then immediately null “”, and sometimes NO UPDATES to the attribute at all.

So my question is, is this explainable by how the integration works, is it possible to change it, or is it just something that is not reliably reported by the devices and so of little practical use, or is this actually a bug?