@Override
	public void remove(Address start, Address end, Register register)
			throws ContextChangeException {
		if (!start.getAddressSpace().equals(end.getAddressSpace())) {
			throw new IllegalArgumentException(
				"start and end address must be within the same address space");
		}
		RegisterValueStore values = registerValueMap.get(register.getBaseRegister());
		if (values != null) {
			values.clearValue(start, end, register);
		}
		invalidateReadCache();
	}
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