The following commands can be manually added to your command table through the TSO ISPF option 3.9 (Application ID:CTLI) or you can copy this table from the Endevor table library from library (dataset iprfx.iqual.CSIQTENU member CTLICMDS).
This table was updated to include 2 entries for controlling the LEFT or RIGHT command when entered from the command line (normally by hitting PF10 or PF11).
These are the commands:
VERB T Action
LEFT 4 &VARC1LR
RIGHT 5 &VARC1LR
Another cause for the left / right schrolling error can occur if the clist that brings up Endevor does not have the word PASSLIB -
"ISPEXEC SELECT PGM(C1SM1000) NOCHECK NEWAPPL(CTLI) PASSLIB"