Interesting....So I just got two new in-box Pixel XLs from Google. Today I sat down to unlock the bootloader & root. When I did the first one, on booting into TWRP using fastboot, I get a screen that says 'Mount, Decrypt Data', asking for a password, giving me a chance to cancel, which I did. I thought it was odd that the 'sdcard' directory was garbled when I looked with TWRP's file manager. But I flashed TWRP & SU anyway, and it seems to have worked fine. I guess. Anyway, I did my wife's phone EXACTLY the same way and I'm not getting the same message when booting into TWRP, and looking into the 'sdcard' directory is completely normal. Any ideas?