Did some more testing. 5W input.
With 50 ohm dummy load, can get red LED to almost go out which corresponds to almost no reflected power confirmed with independent meter.
Detuning slightly shows red LED is at full brightness at about 1.3 SWR (with resistive bridge in 4S Tuner switched in). This corresponds to about 2.0 SWR into antenna alone. So I guess I simply was only able to tune to slightly below 2:1 SWR with certain antennas. Looks like it was really operator interpretation error!
Thanks for the responses from all.
Sent from NM3A