Good morning @Godber and @DLH –
As @instacks points out, sometimes stacks just aren’t compatible with one another because of how they function. That said, if either @DLH or @Godber want to send me an email with a ZIP file containing a simple project file that shows this problem, along with a copy of the gallery stack you’re attempting to use, I will see if I can’t take a look at it.
Also, while I’m here – have you tried using the Gallery stack that comes with Foundry already in your project instead?