I don’t know why, but auto layout won’t work on instances, only on the main component or on the detach instance. Is it a known bug? is there a workaround, beside detatching the instance?
Your spacer has fixed dimensions. If you want dynamic size inside your instances than you need to make spacer hug contents by default. I place a simple rect with dimensions I need inside hug contents layout so the final size isn’t set on the component level, but it’s defined by internal layers.