It is up to the third party manufacturers to make their products compatible with one another. In your specific case, you are using a third party hub along with a third party SSD. In order for macOS to even recognize the SSD requires that the SSD works in the Ice Box Hub. Have you confirmed these two items work together by testing on other computers, especially a Windows or Linux based system?
How is they Icy Box Hub connected to the Mac? Need specific and exact links to the cables & adapters used since they may make a huge difference, plus a link to the Icy Box Hub you are using since I don't know what you have and there are multiple possibilities. Also, what it the exact make & model of both SSDs....are they installed into this hub or do they have their own separate adapter/dock/enclosure? The 1TB NVMe and the older 250GB one? This is also extremely important to know. Not all SSDs work with all computers, hubs, docks, adapter, or enclosures. Yes, theoretically they should, but in my own personal experience this is not always the case.
Make sure to disconnect all other external devices in case one of them is causing a problem.
My guess the issue has something to do with the SSD being used or possibly the cable being used or how everything is connected.