First off I didn't see anywhere you specified the details of the obd2 scanners so that first off we could know whether or not you're using the wrong hardware. I own a 2000 LS myself and kind of assumed any Bluetooth/wifi or usb obd2 adapter would work without issue ;but NONE WORKED!!
The frustrating part is that they would half way kind of connect , like in Torque and the Ford Android app it would look like it's connected fine ;but scanning never worked.
Instead of just creating a new thread and waiting to be spoon fed the magickal solution from the all knowing LS Elite Owners Group here on the forums (nothing against anyone choosing otherwise).
I took the initiative to scour threads for hours collecting data and came into the knowledge that Gen 1 (and possibly Gen 2??) require a pinout that's compatible with MS-CAN and non working adapters can have the pinout changed in order to be able to communicate ;but buying the right adapter from the hop is the easiest way if you lack basic soldering skills.
The exact unit I bought is a USB obd2 adapter with CAN switch, I went with USB because hard line connection is far superior to either BT or Wifi.
I also bought this specific unit because it was confirmed to be Forscan compatible and I have a computer built into my car that's running Windows 10 and Forscan with Extended License (free)
For any gen LS Forscan is the must have software, for Gen 1 LS you can program remote entry key fobs with ease and doing this on Gen 1 LS prior required blood stained underwear and a months worth of Chipolte Away to heal the damage inflicted by the stealership's deep penetrating billing policy lol.
You don't list the adapters that don't work or the one you say did connect or the settings, you don't give any details of the software you're using or the platform you're using it on.
You did explain what's going on technically ;but narrowing down the exact root of your issue is going to require actually having information to critically process what's actually happening.
You also don't say whether or not the car is running while you're trying or if you're moving or what position the ignition is in (on-acc-run).
Long winded comment aside as a 2000 LS owner that's faced the exact same thing I'm betting on you not having the right Modified Elm 327 adapter.
Here's a link to the exact one I bought,
https://www.amazon.ca/gp/product/B0744KSPTC/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
You can go with a Modified Bluetooth or Wifi one if you don't want USB, as I said I chose to get a USB adapter for a couple reasons other than superior connection quality. A big factor for me is using Windows 10 and a laptop VS using a cell phone or tablet and hokey/almost malware like programs that basically only give you read access to DTC codes and the most basic of information.
If you have some tech/soldering skill the pinout on regular obd2 adapters can be changed to work as MS-CAN by swapping 2 pins, or you could solder in a toggle switch to switch between the 2 CAN busses (Correct me if busses isn't the correct term it just felt right).
Anyways I hope you're able to gain a little insight from my long winded borderline rant lol
Give some of the details I asked for if you were trying the proper Elm modified adapters switched to MS-CAN and still facing the same issues.
If not.... ahaha yeah right if not.
