Measuring D1 in circuit applies a voltage between the IC input pins also. I'm guessing that reading is due to a current path in the IC via its input internal protection diodes. ICs generally don't like voltages (from the DMM on Ohms range) applied to their inputs if their power supply is switched off.
The AC caps arrived so the snubbers are installed and this little beauty of a circuit works exactly as planned. Thank you Alec, I am truly impressed with the way you can manipulate parts to get the desired result. You come up with amazing and creative solutions.