Hey Andy,
Try using the contextual-menu or the gear-menu of the insert-text-by-typing action to “Process Nothing”.
You may also want to play with the Set Action Delay action.
You're not the first person to report issues similar to this:
Sometimes Trouble With Insert Text by Typing
Insert Text by Typing Works Sometimes and Sometimes Not
Insert text by typing > slow? - #10 by peternlewis
-Chris