Yes, it should... but can you be certain that it IS the original wallet file? 2.5 years is a long time ago... and there is no real way for us to know exactly what you backed up to USB. I still think it might be more likely that you've backed up the wrong file and the wrong seed, it's the only explanation for the fact that your seed is generating addresses that have no coins (and your original wallet file gives you that same seed)...

I'm fairly sure that if you opened the true old file with your coins in it, in a new version of Electrum, that your coins would be available. The only way for this not to happen is if your file was either corrupt (but Electrum should detect this and tell you) or you are opening a file that is not the one with your coins in it.

At the end of the day, I guess it doesn't really matter... either way your coins seem to be gone

Do you still have the original Tails OS on the USB? Does it boot at all?