@Override
	public RegisterValue getDisassemblyContext(Address address) {
		RegisterValue defaultValue =
			getRegisterValue(baseContextRegister, address, defaultRegisterValueMap);
		RegisterValue currentValue =
			getRegisterValue(baseContextRegister, address, registerValueMap);
		if (defaultValue == null) {
			defaultValue = defaultDisassemblyContext;
		}
		else {
			defaultValue = defaultValue.combineValues(defaultDisassemblyContext);
		}
		return defaultValue.combineValues(currentValue);
	}
if the address is in an overlay and we are getting the default value, then get the default
value from the base space, not the overlay space.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/util/AbstractStoredProgramContext.java