On the Transitions tab go to the Advance Slide group and untick the option for On Mouse Click. Press the Apply To All button to apply this setting to all slides. This will mean you must click on your trigger to advance the slide and use the on-screen tools.

Yes, that can prevent the "click" from advancing, but I don't want to lose the click advance for the slides. What I want is for my slides to not advance even if I trigger what would be a "normal" advance, until I have set off my paragraph triggers.