Block Entity data (e.g. signs) disappears until reloaded

Expected behavior

Block Entities (e.g. signs) should reliably keep their data saved and visible without manual interaction or a full server restart.

Observed/Actual behavior

• Sometimes Block Entity data disappears – the block itself remains (e.g. a sign outline), but without any data.
• In the .mca files, the Block Entity data is missing.
• Using F3+I or /data get block x y z restores the data, and it then persists after rejoining.
• After a full server restart, the data also saves and restores correctly.
• Only once, a sign disappeared again after being restored (possibly time/chunk related).

Steps/models to reproduce

Since the timing of the bug cannot always be determined and it cannot be easily reproduced, there are currently no reliable reproduction steps available.

Plugin and Datapack List

Plugins: Arceon, AxiomPaper, BlueMap, ezEdits, FAWE, goBrush, goPaint
Datapack: custom world height (64 sections, 1024 total, min_y = -128, logical_height = 780)

Paper version

Checking version, please wait...
This server is running Paper version 1.21.8-39-main@616a879 (2025-08-18T02:25:55Z) (Implementing API version 1.21.8-R0.1-SNAPSHOT)
You are 19 version(s) behind
Download the new version at: https://papermc.io/downloads/paper
Previous version: 1.21.8-11-a5f2f61 (MC: 1.21.8)

Other

The server is currently 19 versions behind. Since the bug cannot be clearly reproduced and its origin is uncertain.

Recent changes in newer versions (#40–#58):
Looking through the changelog, none of the recent commits explicitly mention fixes for Block Entity saving/data loss.
Most changes are related to APIs, event handling, DFU backports, and various bugfixes unrelated to chunk or Block Entity persistence.

Could this issue possibly be related to the custom world height configuration?

Start by reproducing the issue on the reported Paper version with the listed plugins and the custom world-height datapack, then compare behavior after updating Paper. Inspect the affected chunk and its .mca data after signs lose their contents, and use F3+I or /data get block x y z only to confirm restoration. Done means block entity data remains visible and persists across rejoining and server restarts.