[Android Central Question]

I'm using an LG Q7+ phone with Android 8.1.0. I looked in settings/developer options but its not there. (it used to be there in earlier versions.)

[B. Diddy]

Welcome to Android Central! Are you sure it was called "USB Mass Storage"? That feature was only available on much older Android devices whose internal storage was partitioned into separate App Installation and "Internal SD" partitions. The Internal SD acted like an actual SD card, and that's what could be mounted to a PC as USB Mass Storage -- when that was done, the Internal SD could not be accessed by the phone, since it was mounted separately to the PC. When Android phones went to a unified storage system, this went away. Using MTP (Media Transfer Protocol), the directories could be accessed by both the PC and the phone at the same time while connected via USB.