At several occasions now, my trackpad two-finger-scrolling stops functioning as it should after some time of using the system. It seems the gesture is still recognized, but it is handled incorrectly: rather than scrolling 'within' the selected window, the whole window seems to 'bounce' indicating I can't scroll any further. Scrolling with an external mouse works fine, as does scrolling with the touchscreen, as does moving the mouse to the scrollbar and click-dragging.
I have updated all latest drivers, except the BIOS which is on A06 since I do not want to upgrade it (yet) since the higher versions currently cause the screen's brightness to flicker. Unless this BIOS is known to address these issues (not listed in the details) I do not see a reason to upgrade it (again).
Worth noting is that this issue only seems to arise after some time of using the system (possibly after a few sleep sessions?).
I pinpointed my specific problem to be isolated to Google Chrome. It is only in some Chrome tabs that I can not scroll. A simple page refresh in those tabs does not resolve the issue. However, opening new Chrome tabs allows me to scroll in them again.
In summary, this seems to be an issue with Chrome (In combination with trackpad drivers? Don't really know how the two work together).
As to 'it occurs randomly', I believe (although not verified) that it occurred a few times again after hooking/unhooking an external monitor (HDMI).
I have since started using Microsoft Edge, since the new version has some of the Chrome features I was missing, and Chrome on the XPS 9550 for me runs rather sluggishly. (Looks like it is not fully HW accelerated).
Mine is not isolated to only chrome! It is throughout the whole operating system and the only fix is a full restart, it is annoying as I use the two finger scrolling very much.
Same problem here. It's only started happening since the Windows 10 Anniversary Update which got pushed to my XPS 2 days ago. Before that, no problem. Now 2 finger scrolling stops after going into hibernation (haven't tested sleep). The only thing that brings it back is a full restart. The problem happens with all applications and even with Windows Explorer (when scrolling through a folder for example).
It isn't the end of the world, but it's bad enough that I no longer use hibernate, which means having to reopen all of my various programs to get back to work.
One other thing I'll note.... I use Adobe CS6 programs which have the App scaling problem (where the interface is tiny) and the "fix" for this problem (telling Windows to look for an external manifest file) reset after the Anniversary Update. All the manifest files I created were still present, but the key I added to the system registry was gone and I had to recreate it. Just adding this information because I suspect there's something that changed in the registry related to the Dell trackpad, that might lead someone to a fix to the problem.