Hello leeewayyy,
Thank you very much for noticing this behaviour. I was able to replicate this and indeed is very strange.
However, I have updated the mbd_mpc574x_ec_toolbox.mdl file, that I was also attached to this response, so please backup the mbd_mpc574x_ec_toolbox.mdl file and then replace it with the one attached.
The file is located under [Toolbox Install Path]\mbdtbx_mpc574x\mbdtbx_mpc574x file.
Hope this helps,
Marius