The bug
There is no command feedback anymore when you successfully trigger a trigger. This affects using /trigger without a mode and value (implicit add 1) as well as providing a mode and value.
In 1.12.2 the feedback was:
Trigger [objective_name] changed with add 1
Trigger [objective_name] changed with set 1How to reproduce
Create a
triggerscoreboard objective/scoreboard objectives add triggerObjective triggerEnable the trigger for you
/scoreboard players enable @p triggerObjectiveTrigger the trigger
/trigger triggerObjective add 1
I will be watching