I notice one interesting problem with the new negative -s mode since 3.1 -- query behaviour seems to differ to the point that innocent queries that run properly in positive -s mode fails in negative -s mode.
The code below demonstrates it (note: the problem only shows with splayed tables):
/ Start with negative -s in command line
/KDB+ 3.6 2019.04.02 Copyright (C) 1993-2019 Kx Systems
/w32/ 8()core 4095MB me my-host xxx.xxx.xxx.xxx NONEXPIRE