That's weird. From my knowledge, there are only 4 ways for making a table control invisible: CXTAB_CONTROL-INVISIBLE different from space, CXTAB_CONTROL-COLS[*]-INVISIBLE different from space for all columns, screen variant activated which hides the table control, or a table control variant with all columns hidden).
Make sure the scrolling does not execute code in your program which would change the INVISIBLE field (every scrolling triggers the PAI, by changing the TOP_LINE of the system variable assigned to your table control in CONTROLS ... TYPE TABLEVIEW ...).
Also make sure that the LOOP on the 2 table controls are defined in the same order in the PBO and in the PAI (weird effects if not done this way).