I have the same issue since upgrading from 2.3 to 2.4.
Unfortunately your solution described does not work for me. No matter whether I put the bank account first or second for a journal entry it will insist on the counterparty entry which defaults some vendor and can't be changed therefore making these entries impossible.
I am currently on version Version 2.4.3 Build 09.12.2017, does the latest 2.4 build fix this?
While I am sure there are good reasons for this feature, it strikes me as a little troublesome that there does not seem any way to either disable it nor prevent the automatic opt-in that seems to have resulted from the upgrade.
If this requires a tweak to a config file I am comfortable to do this... that said the documentation of this feature in the Wiki is virtually non existent which doesn't help either. I would be grateful for pointers on how to fix this.
Thank you.