Hi Chris,
About the first question, there is no known problem with Tbox #0 but remember that the Tbox index must be in order from top to bottom and left to right for each video line. So T-box #0 should always be the first Tbox defined in this order. Would this be the case or not?
For second issue, there is a known issue which there is an offset of 6. So
final x pos = instruction x pos – 6;
If the position is less than 6, value will be negative and will not be displayed properly.
Regards,
Dominic