It would appear that the QR Code encoder (or decoder) is not including something during (de)serialization that the Ledger plugin requires... It's quite possible the code that fixed the issue for the other issue was not included into the Ledger plugin, but should have been.

If you haven't already, I would suggest that you log an issue on Github: https://github.com/spesmilo/electrum/issues

Include the relevant log file date in your issue report and don't forget to mention that you're using a Ledger Nano S.