Love the app but the Copy functionality has bitten me a couple times now, one time with a loss of data (or what I think was loss of data).
Firstly, it would be nice if 'Copy' was renamed to what it actually does which is duplicate. With most other apps, 'copy' means copy to clipboard so you can paste somewhere else.
Secondly, when I copied a task with 'done' subtasks, those done subtasks weren't copied over. Then I ended up deleting the wrong task (since the order was different than I expected after the copy). I couldn't get back the 'done' subtasks after that. But, this could have been something I did wrong since I wasn't able to repeat that exact problem. But there was a new problem with not retaining what subtasks are already done in the copy. I'm guessing this might be as-designed but, for the particular use-case I had, it was unexpected and not wanted. Maybe it could be an option whether to retain the done status on a copy.
Thirdly, as I just mentioned, after the copy, the order within subtasks changed in the copy. This can also be a bigger problem if you use a few subtasks as headers for other subtasks like I did.