I've managed to speak with Sky Store Tech Dept. They've been noticing a rise in this issue over the past 6+months.
it doesn't help matters that RoI CS doesn't have access to Sky Store accounts & vice versa. Resulting in a back & forth of of each saying that the problem isn't on their end, it's on the other dept.
Were you seeing an error code 1100? If so, it's a hardware issue, there is a latency issue with the Sky Glass. It's currently being investigated.
Basically the connection between SG & the router isn't fast enough (nothing to do with your Fibre/Broadband speed), & times out causing the Error 1100, then because it repeats this process the back end systems perceive each attempted connection as a new device.
You'll need to contact Sky Broadband tech support, explain the situation, they should be able to do a reset of registered devices & then talk you through how to improve the latency between your router & SG/Store App.
Hardwiring the SG to the Router via Ethernet is best.
