This is caused by an undisplayable character – I think the only wat you can get around this is to replace the undisplayable character. Your device cannot phyically display the character – it’s not a program problem. Even the licensed programs like Query can’t display certain character combinations.
Also, you should be able to trap a session or device error using the MONITOR operation code (if you’re using RPG IV). Try putting a MONITOR block around your EXFMT or WRITE operation for the display file, and then you could add any error handling you wanted. The device errors I usually see are either the message IDs RNQ1251 or RNG1255, so you could add the appropriate one to an ON-ERROR section of the MONIITOR block.
Perhaps you could then attempt to find and remove the non-displayable characters and then redisplay the screen.