Discovered a little weirdness in ADSB's user interface, that could result in missed data if not understood. In particular,

the ADSB MIL filter works a little different from the other filters.

What I observed:

Had MIL filter set

Added SPECIES = HELICOPTER filter

Result: Only helicopters that are military

Unchecked MIL filter

Result: Only helicopters that are civilian

(Military helicopters are suppressed)

Deleted MIL filter

Result: All helicopters, both military and civilian.

I would have thought that disabling vs. deleting the MIL filter should have an identical effect, but they don't act the same.