I run 3 servers out of the same instance of RustDedicated.  Have for years. 
I can boot 2 of the 3 servers, the 3rd will give me a compiler fail and won't load any plugins.
Any suggestions, other than breaking the 3rd server out of mix and running it on it's own folder?

Well did you tried to load them one by one? Server 1, then after loading 2, etc

Sure did.  I even tried different combinations of booting servers.  All different combinations of 2 work, but if I try to load the 3rd, no matter which one it is, the compiler will fail.
Does that make sense?

Please check your oxide/logs for errors, as they should give a good indication as to why.

For whatever, reason I was able to get them all running from one instance.  Of course not before I broke them all out into their owner folders first.  But whatever.  I guess it was just me.  Problem solved.
Thanks for your responses, both Wulf and Orange.  I appreciate it.