I think they’ve fixed it in the latest firmware package. So, blinky works just out of the box, even if you add UART (I use LPUART in my latest firmware).
Do you have anything connected to your module besides power line and antenna? 1.2uA is a very low current, can be leaking via some pin just because you still have LED or debug interface connected, even if you do not use them. Or if UART wires are still connected. Anything.
What it also can be: power regulator, decoupling capacitors leaking etc. And you are using LoRa-E5 module (not board), right? Like you’ve made your own PCB and soldered it all together and nothing is galvanically connected to the module besides power and may be antenna?
I am also not sure about 1.3uA much better than 2.5uA. It’s about 10.5 mAh per year of difference. Even CR2032 has like 235mAh. You are not going to run your device on CR2032, do you? You still need a lot of power to drive the radio. 1.3uA is achievable in sleep, but below certain value it doesn’t matter any more because most of the power will be spent when device is doing something useful.