Looking at the last photo you posted there, is that an ELT antenna and a COM antenna right next to each other?
Most ELT installation instructions specify something like 4 feet minimum between the ELT and any COM antennas.
I have seen cases where the ELT would be activated when the COM transmitted on certain frequencies. This was with the old 121.5 ELTs though, I would guess the new 406 elts may have better shielding.