Must be due to an upgrade in pxplus that causes this perhaps due to object properties? I dont know if any PRM would help you here.
Can you add an err=*NEXT to your controls... This must be some legacy code?
0010 BEGIN
0020 MULTI_LINE 115,@(10,10,10,10)
0030 MULTI_LINE 115,@(10,10,10,10),ERR=*NEXT
0040 ESCAPE