Sounds like the Range setting is doing its job. As you are hitting the end of travel, the encoder error is increasing. Once it exceeds the r setting, it will flash an error. It also could be the current warning setting (yellow Led with trimpot adjustment).
You have to get use to knowing the flashing speed by experimenting. I am adding a read command that displays the error in my next s/w version.
Are you able to jog it both directions ok when not near a limit ?