Well there's your problem. You're still using RxTools/mset/menu/browser/garbagehax.
You should join the Arm9Loaderhax Master Race and join us in instant 100% boot rate glory.
It was moved to rxtools\sys\code.bin
You need to use another URL to launch if using the browser: https://dukesrg.github.io/?rxTools/sys/code.bin
Launching by other methods works as normal.