Cloudbuild Performance reporting: how are exceptions grouped and how can I find older ones

I have Performance reporting set up and working nicely. Similar exceptions are grouped, which is a useful feature. However I have two questions:

1) When I have multiple exceptions with a slightly different message, in this case a simple Array index out of range exception but with the date and time prepended, messages are still grouped. What determines which exceptions are grouped?





2) How do I reach older exceptions within the same group? Currently it looks like the interface only allows me to see the latest exception.


Best,
Mattijs