Recently viewed products shows visited products by one single visitor. Yes, it is bind by each visitor. If you made it work for all users without changing any code, most likely it is false. The block you say you added on homepage may be full page cached and homepage may look the same for all users.
I guess you could try to make a plugin on function
Magento\Reports\Controller\Adminhtml\Report\Product\Viewed::getItemsCollection()
This function has this:
if ($this->getCustomerId()) {
$this->_collection->setCustomerId($this->getCustomerId());
}
You could try to setCustomerId(null) on recently viewed block.
Or create your block and inherit from Magento\Reports\Controller\Adminhtml\Report\Product\Viewed
class or just from class Magento\Reports\Block\Product\AbstractProduct
.
If your block gets cached in full page cache type, than it's another issue but can be done.
category List pages
,My account pages
,Home Page
andShopping Cart Page
.