I noticed that my display would flash black for ~1 second when the timeline ended/restarted. I spoke to support via live chat, and I was told that this is expected - this is normal. I was told to expand my timeline to have fewer black screens per day.
I understand that this is a limitation, but I have the feeling that there are no plans to get rid of the black screen. I find it to be tacky and unattractive.
Ideally, the player would loop seamlessly, but even leaving the background color/image up would be better than an attention-grabbing black screen.
I understand that this may not be a bug, strictly speaking, but it is an opportunity to improve an already good tool.