Recently, I've noticed that a TM for fragments I'm using had been inadvertently set to Preliminary matching instead of Automatic.
The symptom was that when a new fragment was added, it was highlighted in the source segment, but if I returned to the same segment, or another one with the same fragment, it was not highlighted anymore.
After changing this to Automatic, I've noticed that the setting did not take effect immediately. I had to reopen the project for that.
I think it would make sense to have the preliminary matching is discarded if the option Automatic is selected instead, so that the Workflow integration change is reflected with no project restart.