Success! Looks like we've fixed this one. According to our records the fix was applied for
Senca Cmd change build directory
Can not change destination with this command parameter
I have to change build.dir in in build.properties
sencha app build --destination /path/to/my/custom/destination
I opened a bug for this earlier today actually. I found that you can use sencha config first:
I tested this with Cmd 126.96.36.199, haven't tried with Cmd 5.x but in this case it shouldn't be that different.
sencha config -prop build.dir=/path/to/dir then app build
Sounds like Cmd is not respecting the destination argument. Thanks for the report! I have opened a bug in our bug tracker.