More examples of the power of infrared.
Noticed the moisture in the door trim immediately on initial scan when shower had just been turned on for testing. Confirmed moisture in the trim with moisture meter. Location was unusual in my experience - I have found other leaks in this development - and was subtle.
But it was enough to cause me to Spend extra time investigating the shower. Let the shower run for a while aimed in different areas of the shower seat. That produced the second and third pictures - these confirmed/prove leakage as water was visible on floor, in addition to being visible behind tile to the infrared.