Electrum + Trezor - Rename address labels only allows one label to be defined

Question

Using Electrum 2.3.3 on Ubuntu 14.04.2 with a Trezor (firmware 1.3.3), I'm having trouble with the account labels.

When I rename an account, it displays the new label. However, when I rename another account, the first one I renamed goes back to being "Account 1". It doesn't seem to retain my changes.

Thanks for any help you can provide, and let me know if more information is needed.