Ref T13283. Currently, each Editor sets its own group ID, so if you create a revision and then Herald does some stuff, the two groups of transactions get different group IDs.
This means the test console is slightly misleading (it will only pick up the Herald transactions). It's going to be misleading anyway (Herald obviously can't evaluate Herald transactions) but this is at least a little closer to reality and stops Herald actions from masking non-Herald actions.