Hi ,
I am sorry I didn’t provide detailed instructions the first time around. I just tested the bug again, this time with 4.16.2 instead of 4.15 and with a clean project. Here are the more detailed reproduction steps:
Reproduction Steps
Create a new Blueprint Project
In the Project settings under Input add an Axis Mapping for the Pinch key and name it “PinchAxis” or whatever you want.
Also set the Default Touch Interface to None.
Create a PlayerController Blueprint and add an Axis Event node for the Axis Mapping to the Event Graph.
Connect the Axis Event’s execution pin to a Print String node and the “Axis Value” pin to the “In String” pin.
Create a Gamemode Blueprint to select your PlayerController BP.
In Project Settings → Maps & Modes select your Gamemode Blueprint as the Default GameMode and Template_Default as the Game Default Map.
Package the Project to test it out on your mobile phone and start the app once it is installed on your phone.
Start touching your phone near the edge of the screen with one finger.
Move that finger towards the middle of the screen without lifting your finger.
Touch the your phone on the opposite side of the screen with a 2nd finger without lifting the first finger.
Try to lift your fingers without moving and exit the app.
Locate the log file on your phone to see the result.
Result
The Pinch Value is 0.0 until the second finger touches, at which point the value is 1.0 for the first frame. After that the value is somewhere above 1.5 or below 0.5 until the fingers are lifted.
Expected
I would expect, that the value does not jump to a different number on the frame after the second finger touches. I would either expect the number to be something like 1.5 or 0.5 on the first frame, or I would expect the number to be something like 1.05 or 0.95 on the second frame.