Ok that my issue, I used the same glcall which expect a location of 0. I was wrongly expecting location to follow the layout binding semantic. I guess "binding" is linked to image unit not "bindless uniform". Is there any way to specify a default location with layout, or is it a limitation of the extension? Might worth to add an error/warning that said "bindless sampler and binding layout property are incompatible".
Is there any chance you're not using the correct location value for "TextureSampler"? For me, if I compile with PS_ATST with 6 then "TextureSampler" gets a location of "1" (and not 0). However, if you try to
call glProgramUniformHandleui64vARB with a location of "0" then you'll get "Element is invalid".