Caveat, totally wild guess, I’m not an electronics engineer, touchscreens are AFAIK a whole science on their own, and we don’t know how the FP4’s one works anyway (there are several methods).
All we know is that there is some empirical evidence that the FP4’s touchscreen now requires the phone to be connected to some larger conductive body to reliably work – Either the user also touching the phone’s chassis, or the phone being connected to something else by its USB cable (like while charging it).
Could it be the update lowered the gain of the capacitive touchscreen so much, it now requires some kind of grounding to reliably create any detectable change on the screen’s electrostatic field?
In which case it should be simple to raise the gain back again, just enough to make this annoying side effect disappear (don’t know what this would do to the ghost touches issue though…).
I use the official screen protector by Fairphone. I have the issue when its flat on a table and trying to pinch to zoom. Then the multi toch isn’t registered. You are testing zooming? Just to make sure we’re testing the same thing. There are some other issues as well, but the one on a flat surface is reproducible and thus a great reference point.
Flat on the table, testing both rotating and pinch to zoom. Works as expected 95% of the time. Sometimes effectively seem to have trouble to immediately register the rotation after zooming, without taking away the finger. If you remove the finger and touch again then you can rotate normally.
As I said, no screen protector.
I use a BROTECT AirGlass Matte Glass Screen Protector.
Tapping and swiping is good. If hold the phone in my hand no problems with zooming or typing.
But zooming or typing is not working when the phone is flat on the table.
As I never use the phone flat on the table, I don’t know if I could before the update.
I don’t use any kind of screen protector, so it’s apparently more complicated.
Apparently there is even simpler: Just plug a USB cable into the phone, doesn’t need to actually be connected to anything! I tested it by just plugging the official USB-C to mini audio jack adapter, with nothing plugged in it!
Despite its only 10 cm length, it was enough to restore normal touch sensitivity, so it really doesn’t need much. (YMMV, if it doesn’t work try different cables)
(Test made as always on the same (wooden) table, using Google Maps)
Now I am worried whether I should really try to plug a USB-C cable that is not connected to anything into my phone! The risk of this “hack” is just to high! /s
Edit: just tried it. This works for me too, screen is much more responsive when I plug something in and the phone is laying on a desk with no hand touching the back or sides of the phone. I am using the Airglass screen protector.
I have originally posted my issue in the Ghost Input Thread, but was just redirected here, since that (hardware) issue indirectly relates to this software update, since the update does not resolve the issue but changes its symptoms. In short: The Ghost inputs have been replaced by an unresponsive touchscreen in the corresponding areas, which may cause less unwanted behaviour, but does not restore control over the phone when the issue occurs.
I must say I actually like the new touch sensitivity setting. For the first time ever, I’m able to scroll pages with left thumb while holding the phone in left hand! Bedore this update, it almost always resulted in zooming (as a part of the palm is touching the edge of the screen, creating a second touch point).
Never had problems with touch. Since the update, the screen is less responsive but useable in normal use, but, worst of all, using it with my motorcycle gloves has become hopeless which really bums me…
I have the same problem with a Fairphone 4. I have both data and wifi on and when it switches to wifi, the data disappears and I can’t enable it again. At least from the dropdown menu. To fix it I’m restarting the phone, after which it auto connects to my data network without problem. Mobile data always active is on by default it seems. Gonna update to SP2J.B.086 and hopefully it fixes it?