Huh, I’ve just tried to recreate this, and this is not happening here. Did you modify the code piece?
Are you using a solution/project? In that case, please do a right click in Solution Explorer on the assembly file, choose “Properties”, go to tab “Assembler”, and set it to “C64Studio” manually. It could be that the automatic assembler style detection is thrown off by a code word.
That’s the code I tested with, copied straight from the help:
;startup address
* = $0801
;create BASIC startup (SYS line)
!basic
;increase border color
inc $d020
;return to BASIC
rts