To test this issue, I started typing the message below and then cut off the wifi after the last word below.
I then terminated the instance of chrome that I was using to type my message online.
I waited 10 seconds and then reconnected the laptop wifi to the access point and
I then opened a new tab in Chrome (I had left Chrome running when I killed the wifi)
I reentered groups.io and selected Beta group.
Then I looked at my top draft of 8 outstanding and it was the message you see below
I selected it and was returned to the exact place where I exited from.
Yahoo never did save drafts when connections dropped out.
I reread your message and realized that it's possible you are operating in an email mode with groups.io.
If this is an email mode issue, it's definitely a software problem at your end.
There is no reason to expect the system to continually poll you once you are disconnected