protected void invalidateWriteCache() {
		RegisterValueStore store = registerValueMap.get(baseContextRegister);
		if (store != null) {
			store.invalidateWriteCache();
		}
	}
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