macOS WireGuard GUI - password not accepted when editing a tunnel

[Rich Brown]

I'm using the macOS WireGuard App version: 0.0.20191105 (16); Go backend version: 0.0.20191013 on macOS 10.14.6

I can create an empty tunnel and fill it in. But I cannot edit it: clicking the edit button and typing the password causes the password window to shake. I can however, delete the tunnel, and create it anew.

You can see a video of the problem at: https://youtu.be/XlCS1Cb2ubk

I am certain that I am typing the proper password, using exactly the same keystrokes as I use to log in. (Password is mixed lowercase and digits - no odd characters.) I can successfully log in using the same Wireguard app version (with proper password) on my other laptop (Catalina, 10.15.4).

Any thoughts on why the password would be rejected? Thanks.