5.1.0M1 BPMN RuleFlow file errors editing or loading with 5.1.0M2

After updating from 5.1.0M1 to 5.1.0M2, my BPMN ruleflow files now have errors in the editor and errors loading as resources.
Editor only shows the start node for what was a usable BMPN ruleflow previously.
Editor now complains that property ID is null.
Editor now adds characters to end of name. For example, file "Startup.bpmn" has "Startup.b" in the name property.

Example error:
Description Resource Path Location Type
Unresolved compilation problems:
The method getTextContent() is undefined for the type Node
The method getTextContent() is undefined for the type Node
Startup.bpmn /Project/src/com/rules Unknown Drools Error