Item Frames and anything in them have disappeared

Put the summary of the bug you're having here

What I expected to happen was...:
I expected item frames, the items in them, and the maps in them to still be there when I opened up 1.14.3 Pre Release 3

What actually happened was...:
Instead, all item frames including all items and maps in them, have disappeared

Steps to Reproduce:
1. Have item frames up already via any earlier release
2. Load in 1.14.3 Pre-Release 3
3. See that all placed item frames and the items and maps in them, are gone