I'm having the exact same issue as described in this post: Chromecast with Google TV July update seems to hav... - Google Nest Community
I could previously access the storage using a higher power supply (at least 60 watts), which I am still using, so this is not the issue. I have tried resetting the Chromecast with no change. I can successfully see and access the storage card using the X-plore app but have no ability to see or format it through the Chromecast Settings>System>Storage menu.
Hey there pracom,
I'm sorry to hear that your Chromecast is having issues with your USB Hub! I can imagine this is a pretty frustrating issue, so I'd be happy to help out. Let me just ask you a few questions to better understand the situation:
I look forward to your response, and if you have any other questions or concerns for me, please let me know!