As far as I can tell wheel encoders are working in stable and in the dev version (aka latest, aka 4.0.0). There are some problems (fixes coming in Rover-4.0.0-rc2) but the wheel encoder driver itself works I think.
Your parameters look pretty OK except that the two wheels are in the same place (probably one of the POS_X values should be made negative). Also I think the POS_Z values is unused although it probably doesn’t hurt to have it set.
The log shows that the wheel encoders aren’t working though. I guess you moved the wheels during this logging period? The motors were powered of course? The wheel encoders won’t provide any “pings” unless the motor is powered. I guess you’ve double checked the wiring to make sure it’s similar to what’s shown on the wiki?
Another way to check if AP is correctly reading data from the wheel encoders is to go to MP’s Flight Data screen and press Ctrl-F, then push the “MAVLink Inspector” button (in the middle) and then expand “Vehicle 1”, “Comp 1” and check the WHEEL_DISTANCE messages’s “distance” values. The first two values will be the total distance travelled by the first two wheels.
It might be a good idea to double check with Rover-4.0.0-rc1 which is available using the “Beta Firmwares” link in MP (and QGC I think).