The bug
When you put a full block that's not transparent, it causes the item not able to float above the block.
Linked issues
Attachments
Comments 3
Thank you for your report!
However, this issue is being tracked in MC-134145.
That one's been resolved as Invalid, but the explanation there applies to this situation - flowing water was never intended to make items float to the surface.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Mojang Support – ✍️ Feedback and Suggestions – 📖 Game Wiki
Confirmed for 1.13.1.