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>> Did I lose my coins? How did it happen?
>> I read about people who had similar problems with CB and Electrum transfers when asked to wait 72h but got their coins eventually
Seems like it, just a few minutes after you received the funds from CB, this transaction occurred:
587645349fb0e5ceb23498d4ae9862e3d157765539e14cb988fe626e8e868ae8If you did not initiated that transfer, It's highly likely that your Electrum is compromised via a couple of factors or you're using a fake version.
Unfortunately, Bitcoin transactions are irreversible.
All you can do is to check the reason of the hack and learn from it.
It's definitely not a fake version. I updated, installed, uninstalled. What factors could be involved? I'd like to know if it is indeed compromised and how that could happen.