There was a mismatch between the shader msaa super variant and the Render target sample count. Addressing that fixed the following Vk error
<16:36:09> [Error] (vkDebugMessage) - [ERROR][Validation] Validation Error: [ VUID-RuntimeSpirv-samples-08726 ] Object 0: handle = 0xbfd2530000000a6d, name = DiffuseProbeGridRender_PassSrg, type = VK_OBJECT_TYPE_DESCRIPTOR_SET; | MessageID = 0xdba6a50a | vkCmdDrawIndexed: Descriptor set VkDescriptorSet 0xbfd2530000000a6d[DiffuseProbeGridRender_PassSrg] in binding #1 index 0 requires bound image to have multiple samples, but got VK_SAMPLE_COUNT_1_BIT. The Vulkan spec states: If an OpTypeImage has an MS operand 1, its bound image must not have been created with VkImageCreateInfo::samples as VK_SAMPLE_COUNT_1_BIT (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-RuntimeSpirv-samples-08726)
<16:36:09> [Error] (vkDebugMessage) - [ERROR][Validation] Validation Error: [ VUID-RuntimeSpirv-samples-08726 ] Object 0: handle = 0xbfd2530000000a6d, name = DiffuseProbeGridRender_PassSrg, type = VK_OBJECT_TYPE_DESCRIPTOR_SET; | MessageID = 0xdba6a50a | vkCmdDrawIndexed: Descriptor set VkDescriptorSet 0xbfd2530000000a6d[DiffuseProbeGridRender_PassSrg] in binding #1 index 0 requires bound image to have multiple samples, but got VK_SAMPLE_COUNT_1_BIT. The Vulkan spec states: If an OpTypeImage has an MS operand 1, its bound image must not have been created with VkImageCreateInfo::samples as VK_SAMPLE_COUNT_1_BIT (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-RuntimeSpirv-samples-08726)Related linked PRs Core engine - https://github.com/o3de/o3de/pull/16625 3p package - https://github.com/o3de/3p-package-source/pull/212