Player: what do you mean by "Run with -Dfastcraft.asm.permissive (before -jar) to work around the issue until it's fixed, there shouldn't be negative side effects."
Sorry this one really confused me. xD
You start the server with "java -jar forge-version.jar nogui" or similar, replace that with "java -Dfastcraft.asm.permissive -jar forge-version.jar nogui" to activate the option. If you use some server admin panel, you'd have to look for where it allows to specify additional Java parameters.