The bug

In the Pocket-style inventory armor tab, you can see your armor points. This bar is supposed to remain in place.

... but if the player has lots of health, it moves down, and can even disappear entirely:

The definition in the UI file inventory_screen_pocket.json has a field that specifically attempts to avoid this issue:

"armor_renderer": {
  "type": "custom",
  "size": [ 1, 1 ],
  "offset": [ -40, -5 ],
  "layer": 2,
  "renderer": "armor_renderer",
  "anchor_to": "top_middle",
  "anchor_from": "top_middle",
  "property_bag": {
    "#use_heart_offset": false
  }
}
 

However, it doesn't work (anymore). It's unclear exactly when this stopped working.

How to reproduce

1. Use pocket edition UI
2. /effect @s health_boost 100000 29 true
3. Open your inventory and go to the armor tab

Expected result

The armor bar should be in the normal place

Observed result

It's moved down a lot