Can you please provide more info? What version of JER, which modloader, a log file, ...

Having the same issue. Tried viewing recipes for a slime ball and I only see how to get it via wandering trader but not from slime drops. This is on a private multiplayer server.

debug.log

Minecraft: 1.20.1
JER: 1.4.0.247
Modloader: NeoForge 47.1.106

Mods

antique-atlas-2.9.17+1.20.jar
appleskin-forge-mc1.20.1-2.5.1.jar
bellsandwhistles-0.4.3-1.20.x.jar
Botania-1.20.1-446-FORGE.jar
Cobblemon-forge-1.5.2+1.20.1.jar
configured-forge-1.20.1-2.2.3.jar
Connector-1.0.0-beta.45+1.20.1.jar
Controlling-forge-1.20.1-12.0.2.jar
create-1.20.1-0.5.1.h.jar
curios-forge-5.10.0+1.20.1.jar
entityculling-forge-1.7.0-mc1.20.1.jar
fabric-api-0.92.2+1.11.8+1.20.1.jar
ferritecore-6.0.1-forge.jar
gravestone-forge-1.20.1-1.0.23.jar
jei-1.20.1-forge-15.19.5.99.jar
justenoughbreeding-neoforge-1.20.1-1.4.0.jar
JustEnoughProfessions-forge-1.20.1-3.0.1.jar
JustEnoughResources-1.20.1-1.4.0.247.jar
kotlinforforge-4.11.0-all.jar
memoryleakfix-forge-1.17+-1.1.5.jar
Patchouli-1.20.1-84-FORGE.jar
Quark-4.0-460.jar
Searchables-forge-1.20.1-1.0.3.jar
Steam_Rails-1.6.5+forge-mc1.20.1.jar
StorageDrawers-1.20.1-12.7.0.jar
theoneprobe-1.20.1-10.0.2.jar
Zeta-1.0-24.jar

Hmm appears to work in single-player and I don't see the mod installed on the server. Perhaps this is the issue.

EDIT: I added the mod to the server and this did not solve the issue.