for the past month I was using the following simple configuration to connect my LG G3 both to a webcam and power simultaneously.
Picture of Phone charging and OTG connection to webcam with a three way cable
I have updated the OS version from 4.4.2 (Kitkat) to 5.0 (Lollipop). Now my LG G3 will do charging or OTG, but not both simultaneously anymore.
I was wondering if OTG + charging could be affected not only by models of the device but also by the OS version?
That functionality is purely affected by the kernel bundled with the OS. Lollipop kernels have a lot of changes made, although it might be your carrier blocking the feature. Carriers block a lot of features in this file: /system/csc/feature.xml
Your best bet is to find custom LG G3 kernels on XDA and flash one that does the job.
If none of those support OTG+charge, your best bet is to backup your data and flash the Kitkat .kdz for your model, and fix the stagefright issue by adding this to your build.prop file: media.stagefright.enable-player=false
as mentioned here: XDA