Autocrafters fail to distribute items correctly with hopper-amount > 1

Expected behavior

PaperSpigot 1.21.5-114-ver/1.21.5@a1b3058 (I know the new one just came out, but almost none of the plugins we use are updated yet. Ideally, this will be fixed in a 1.21.7 build.

ticks-per:
  hopper-transfer: 6
  hopper-check: 1
hopper-amount: 8

When using an autocrafter with hopper-amount: 8, items no longer distribute into separate unoccupied input slots as expected. Instead, all 8 items are inserted into a single slot per transfer tick. This breaks most vanilla autocrafter circuits.

Observed/Actual behavior

All 8 items go into the first compatible slot. This causes slot imbalances and prevents the autocrafter from crafting unless manually corrected. This makes it difficult to make a reliable circuit to condense iron bars into blocks.

Ideally, items fed into an autocrafter via hopper would bottleneck to one per tick to be a bit more consistent in terms of vanilla behavior.

Steps/models to reproduce

https://imgur.com/qW02nOx

Plugin and Datapack List

plugins
[15:42:34 INFO]: ℹ Server Plugins (23):
[15:42:34 INFO]: Paper Plugins (1):
[15:42:34 INFO]: - BKCommonLib
[15:42:34 INFO]: Bukkit Plugins (22):
[15:42:34 INFO]: - CartLoader, CoreProtect, dynmap, EpicPluginLib, Geyser-Spigot, InvSeePlusPlus, LuckPerms, MAmbience, Multiverse-Core, NoMobGriefing
[15:42:34 INFO]: PL-Hide, PlayMoreSounds, ProtocolLib, qsaddon-reremakemigrator, QuickShop-Hikari, SuperVanish, Train_Carts, Vault, ViaBackwards, ViaVersion
[15:42:34 INFO]: voicechat, XConomy

(PL-hide, NoMobGriefing, voicechat, and qsaddon-reremakemigrator are all disabled due to incompatibilities)

Paper version

[15:21:07 INFO]: This server is running Paper version 1.21.5-114-ver/1.21.5@a1b3058 (2025-06-18T10:59:02Z) (Implementing API version 1.21.5-R0.1-SNAPSHOT)
You are running the latest version

Other

I was able to work around the issue by feeding the "full" detection circuit into a pulser which should hopefully work well enough to get my farm going again.

Start by reproducing the issue on Paper 1.21.5-114 with hopper-amount: 8 and the listed hopper timings, using the linked reproduction media as context. Trace the hopper-to-autocrafter transfer behavior and verify that items distribute across compatible unoccupied slots rather than all entering the first slot; confirm the behavior with an autocrafter circuit.