Only first label in list works correctly in parallel pipeline call

Today we updated our plugins to the latest available. This included updating Pipeline API from 2.4 -> 2.5 and Pipleline Groovy 2.19 -> 2.20

After we did that, our parallel builds began failing. We have a series of builds that run exactly the same function on several different label's nodes. Only the first action in the list of items submitted to Parallel works – all of the others result in these errors:

[centos5x32] Failed in branch centos5x32
[centos5] Failed in branch centos5
[macosx1010] Failed in branch macosx1010

The first item in the generated list runs fine – all others in the parallel fail with the "Failed in branch"

Here is the code that sets up the parallel

def nodeNames = ['windows10', 'centos5x32', 'centos5', 'macosx10.10'] // labels for Jenkins node types we will build on

def builders = [:]
for (x in nodeNames) {
    def label = x 

    // Create a map to pass in to the 'parallel' step so we can fire all the builds at once
    builders[label] = {
        node(label) {
            commonBuild(label)
        }
    }
}

try {
	stage ('Parallel Build') {
		parallel builders
	}
} catch(e) {
	currentBuild.result = "FAILED"
	throw e
} 

Again, this build ran fine right before the plugins were updated, and failed after. Putting this within a method, and then marking that method as @NonCPS seemed to help – it a least allowed all 4 nodes to start in parallel.