When I downloaded Electrum I didn't check the PGP signature initially.
After the incident, I looked into my browser history (the link was correct), accessed the link from history, downloaded again the installer and checked the signature which verified.
It's possible my initial install was corrupted, not very probable though.
What is weird that I personally have never been alerted by MB (using the premium version) regarding the Electrum servers, which may just be a coincidence, even though I have the servers set to automatic.
I must admit I've never heard of change path attacks, and it will be really weird if this is the case here, because that's supposedly should be fixed. If I understand correctly, in this case, the attacker actually initiates a transaction that does not allow him to access to the funds, but by changing the path hides the funds and then requests a ransom for info where coins are located.
I cannot technically say how this can be done, but there may be a possibility that some of the servers you mentioned may still be guilty of this, although this is just one of the options.
I see you've taken the right steps in trying to find where the coins ended, and I really hope you can find them. I would only advise others to be careful until it is revealed exactly what happened in this case.
I'm hoping more that it's a bug instead of a change path attack (which indeed is supposed to be fixed, so at the very least it's not exactly the same attack), but given that the Ledger is supposed to NOT show only transactions towards the change addresses, I have some hope albeit small.
Thanks for your input.