Some Eaglercraft versions require you to disconnect and reconnect to the server for the transparency to fully take effect.
In standard Minecraft, x-ray packs work by editing terrain.png or using OptiFine’s custom texture properties to set certain blocks to transparent. However, many modern servers have anti-x-ray plugins that obfuscate ore locations or validate textures, rendering simple packs ineffective. On Eaglercraft, server-side protections vary widely, and because Eaglercraft is less regulated than official servers, x-ray packs can sometimes work unhindered. xray texture pack 188 eaglercraft