Don here from Shopify. :)
Did you get in touch with the developers of any of those loyalty/reward apps you were trying to install so they could provide support with their product?
Third-party apps, themes, and gateways are supported by their creators, rather than by us here at Shopify; so you would just need to reach out to the developers of whichever apps you had been trying to use for support.
You can check out a range of these apps in our app store.
If you want to get support with installing a given app, you can use the contact details listed on its app store page to get in touch with the developers who created it who will be able to help you to get it working for your store.
Try it out and if you need a hand with getting one to work for your store you can just get in touch with its developers as outlined.
How are things going with your business otherwise?
We've got the Loyalty & Rewards app in our all-in-one marketing platform, Besides that, you have a choice to enjoy other awesome apps as well.
As for the Rewards program, you may try ours and we will try to investigate what is causing the issue and help you out with it.
Also, we have integration with Shopify POS as well (Starts with Enterprise plan)
Moreover, we have released the new design for the Rewards tab yesterday, you may check it out here on our demo site