3020 PRO MAX - 500W not recognized in gSender

[Shipwreck]

Are you selecting grbl or grblhal at bottom?
you could also try another version and see if you have same issue

Confirm grbl vs grblHAL on connect

I’m seeing a lot of Facebook posts where people are having problems with erratic behavior or errors after upgrading to 1.4.x and almost all I have helped with ended up being the user selected grblHAL when they connected (or it somehow defaulted to that which I find hard to believe) I would recommend some type of confirmation or check that if you can’t read firmware values, you fail the connection. At least something that calls out attention to the board type.