Thank you for bringing this to our attention. This is indeed a bug. Apologies for any frustration it’s causing. We are currently working on a fix! We will post here once that is complete.
Our team was able to use this information to isolate the root cause of the issue here, and we’ve just pushed a fix. The fix is live now — can you please refresh the Designer to ensure you have the latest build? I hope this helps, and thanks very much for your patience while we worked towards a fix here.