Coinbase usually deducts a fee first, but this time it got into the 'Sent' file without a fee, so I just sent more funds to cover it. This transaction has been sitting in 'pending' for 10 days.
When I am checking on the blockchain there is no transaction id. Not sure if Coinbase is holding it or it is not moving because there is no fee included. Do you think it will end up back in my Coinbase wallet? Or maybe an Electrum wallet is too suspicious to them?
I don't think this has anything to do with your wallet being suspicious or something like this. And since there is no transactions incoming to your address, Coinbase hasn't even sent your coins yet. Which means that the transaction is "pending" in their system and not in the Bitcoin blockchain.
Send them a ticket here: https://support.coinbase.com/customer/portal/emails/new