Sorry，My English is bad.
The gui cannot be used after bungeecore cross-server，Can be used when not cross-server，
Don't know if you have encountered.

Minecraft client version：1.12.2
Forge：1.12.2-forge1.12.2-14.23.5.2847
Server version：
Minecraft: 1.12.2
SpongeAPI: 7.1.0-ea50f0c2
Sponge: 1.12.2-7.1.8-SNAPSHOT
SpongeForge: 1.12.2-2838-7.1.8-RC3968
Minecraft Forge: 14.23.5.2847
BungeeCord：Waterfall #384
MOD version：architecturecraft-1.12-3.98