No sound from slave inputs with 440

[Freddie77]

I have had that problems usually after firmware upgrades or hardware upgrades back from the factory.

Usually it is to do with (1) Different firmware versions between the master and the slave;  (2) Connection problem with the link cable;  (3) Sequence of booting up of the master and the slave, master first is usually fine.

As with Murphy's law, Typically it is a combination of the above.  So I would try upgrading both units with the same firmware again, replacing a link cable, and, unplugging both units and re-connect the master first and then the slave.  Usually it is fine.  I have had one incident of a multiple link cable did not want to budge, but it worked in the end with one of the cables.  But for some reason, all cables after that worked fine afterwards.

All the points that you mention above have been checked and are ok. I have narrowed it down to one issue mainly after comparing other people's configs; it seems that when enabling Sharing inputs my configurator somehow doesn't let it work properly (it changes from Chaining to Digital 1); it links both amps and the boot up as mono and everything works fine, but the only inputs that work are on the master and the slave has its inputs silent or disabled. 
I PMed Pim yesterday to see if he can replicate the configuration from his computer. I use iMac with the latest updates, and I have tried the configuration with 3 different browsers using the methods suggested here and sometimes it even gets worse. The only configuration working as I described above is the one made with Safari, with Chrome and Firefox both amps end up as separate 440 units without link.