Thanks for answer to previous q.

New question.
Using test site on wamp with zc1.5.5f, IH5, clone of responsive_classic, SbyA 1.54 for zc 1.5.5f, Colorbox 2.1.2. , One Page Checkout most current, wamp php 7.1.13, one category with one product. Product has 4 size attributes with stock. Product info has 4 additional images (not attribute). Size attribute photos installed via attributes controller. All photos are jpg.

Dynamic Dropdowns set to 0 (off)
SbyA config in Stock - Display Attribute images set to 1. (tried setting as on with single attribute option and radio selected)
Attribute Settings - Enable attribute images set to true.
IH5 set to resize images, on. (also tried with set to off)
Option Name controller- Size attribute set to radio, and display option 6 selected with images per row left blank (also tried 1, 4). (also tried display option 7 and 8)

When clicking on the size radio button on the product page the attribute image is not swapping in. Also tried removing the non-attribute additional images from the propduct info page.

The following error gets logged when attempting to select an attribute:

Code:
05-Feb-2018 01:08:42 UTC] PHP Fatal error:  Uncaught Error: Call to a member function notify() on null in C:\wamp\www\includes\modules\doug_responsive\main_product_image.php:19
Stack trace:
#0 C:\wamp\www\includes\classes\ajax\zcAttrib_prod_info.php(48): require_once()
#1 C:\wamp\www\ajax.php(76): zcAttrib_prod_info->swap_image()
#2 {main}
  thrown in C:\wamp\www\includes\modules\doug_responsive\main_product_image.php on line 19
I note that main_prodcut_image.php line 19 is a merged change from IH5. Beyond that, I haven't a clue what the error means ;-)