when trying to tune my antenna to channel 1 of 60 meters, The ATU refuses to do so. Even the Tune button does nothing. This used to work on 1.10.16 software. 1.11.12 also fails. What happened?
In SSB and DIGx modes, TUNE is done on the carrier frequency to prevent QRM in the receive passband. On 60m, this is a special case because you are at the edge of a channel and emission is not allowed at the carrier frequency because some of the RF energy is outside of the channel designation. You need to tune to a frequency inside the channel bandwidth to use the TUNE feature as indicated by David above.