Resource pack loaded, but not applying

Hi.

So I made a funny (subjectively) little resource pack for me and my friends to play around with, the thing is, the resource pack downloads when I go into the server, but it doesn't work. When I go into the resource pack menu, it does show it as selected with its icon and description, but nothing is changed ingame. My friends are having the same issue too.

The server is on 1.12.2 Forge 14.23.5.2854 with 28 mods installed.

The resource pack works in singleplayer and the file is the correct zip file.

Link is https://www.dropbox.com/s/qkqp139gjs9a6sy/osamapack.zip?dl=1

Quote from Roman

What is the address of the server in question?

The server address is cluckerbell.aternos.me

It requires these mods:

AdvancedRocketry-1.12.2-1.7.0-232-universal.jar

14.38 MB

BetterFps-1.4.8.jar

151.56 kB

CustomMobSpawner-3.11.5.jar

705.34 kB

dooglamoocitiesmod-1.12-1.6.3.jar

503.52 kB

DrZharks MoCreatures Mod-12.0.5.jar

21.40 MB

furniture-6.3.1-1.12.2.jar

2.32 MB

hempfarmer-0.0.1.jar

257.92 kB

Immersive Vehicles-1.12.2-20.4.0.jar

4.17 MB

IV_Trin_Civil_Pack_V2.6.1.jar

27.04 MB

IV_Trin_Part_Pack_2.19.1.jar

6.60 MB

LibVulpes-1.12.2-0.4.2-85-universal.jar

526.79 kB

MCA-1.12.x-5.3.1-universal.jar

3.51 MB

mw_2.0-0.4.6.2_mc1.12.2.jar

33.16 MB

obfuscate-0.4.2-1.12.2.jar

126.07 kB

prefab-1.3.1.4.jar

6.15 MB

ProjectE-1.12.2-PE1.4.1.jar

1.73 MB

r2s-Core-1.12.2-1.7.0.RELEASE.jar

756.09 kB

r2s-Radio-1.12.2-1.4.2.RELEASE.jar

1.25 MB

RadixCore-1.12.x-2.2.1-universal.jar

137.25 kB

thehunt-0.4.0.jar

17.55 MB

UNU Military Pack [MTS] 1.12.2-19.15.5-4.0.2.jar

11.58 MB

UNU Parts Pack [MTS] 1.12.2-20.1.0-4.4.2.jar

13.69 MB

vehicle-mod-0.44.1-1.12.2.jar

2.04 MB

If you want to access the server, the files are here https://www.dropbox.com/s/5t2g…/cluckerbellmods.zip?dl=0

Quote from Roman

Does the issue persist with Vanilla?

On a vanilla server, the resource pack works.

I think it has to do with both the mods and the server interfering, because the resource pack seems to work on singleplayer with those mods but not on the modded server.