Ok... so as it turns out... the culprit was actually "Electrum Pro" 
Unfortunately, the OP had received some bad advice from a third party and had been using "Electrum Pro" to pay the Bitpay.com invoices received when funding their Bitpay card. On further investigation, there had already been a few other instances of funds being stolen... but for much smaller amounts that the OP had not noticed.
There was a pattern where OP would transfer to Electrum Pro, Pay bitpay.com invoice and then any leftover funds would be transferred out at a later time. Unfortunately, this time, the scammers saw the deposit and transferred it out before he sent to Bitpay.
OP is now using bitpaydecoder.org to decode bitpay.com invoices to a BTC address+Amount so they can simply pay directly from their original wallet without needing to use an intermediary wallet like Electrum.
TLDR;
- OP got scammed by "Electrum Pro"
- Bitpay not at fault
Unfortunately, the OP had received some bad advice from a third party and had been using "Electrum Pro" to pay the Bitpay.com invoices received when funding their Bitpay card. On further investigation, there had already been a few other instances of funds being stolen... but for much smaller amounts that the OP had not noticed.
There was a pattern where OP would transfer to Electrum Pro, Pay bitpay.com invoice and then any leftover funds would be transferred out at a later time. Unfortunately, this time, the scammers saw the deposit and transferred it out before he sent to Bitpay.
OP is now using bitpaydecoder.org to decode bitpay.com invoices to a BTC address+Amount so they can simply pay directly from their original wallet without needing to use an intermediary wallet like Electrum.
TLDR;
- OP got scammed by "Electrum Pro"
- Bitpay not at fault
Thank you for the update to because I was actually waiting to know where it would end on whether its Electrum that is vulnerable or something else was responsible for the issue at hand but your uppdate has surely given everybody a closure (for those that have suggested one solution to the other and those that would be reading later) that the real Electrum has not fail yet. I think there is need for massive exposure for people to know the right Electrum to download and the fact that you send and was received does not make the app the right one which is what happen to Op, if the 'Electrum Pro' had not gotten greedy, they would have been removing his fund and he won't know about it. In addition, I think the web needs to be safer anybody should be allowed to pick names similar to what has already been in existence.
