Today, I lost a part of my draft again because of a very similar pattern. Autosave doesn’t seem to work after you click reply and then cancel while you were looking at a topic different from the one you replied to.
Steps to reproduce:
Start drafting a reply to a topic
Write some text.
Navigate to a different topic while keeping the draft open
Click reply and choose cancel in the modal asking which topic you want to reply to.
Write some more text.
Copy the text you have written or memorize your input.
Reload the page/ close the composer.
Navigate back to the topic you replied to
Open your draft.
Everything written after clicking cancel is missing.
In the video, you can see that pasting some text and reloading works fine. Then, after navigating to a different topic, clicking reply and cancel, the input is not saved and disappears during the reload. But doing the same without using cancel in the modal works fine in the end.