Today I noticed that the installed 4GB microSD card was not recognized by my Roku Ultra. I removed it, formatted it on the computer and re-installed it. Then I formatted on the Roku. When I checked the status, it said 100% used! How is that possible? I did not add any apps after I formatted it. In fact, I removed several apps that I don't use. I removed it and put it in the PC and it shows it's empty. Put it back in the Roku, formatted it again and noticed that after it finished, a quick message about refreshing channels (I don't remember the exact wording) and again it shows 100% full. Even if it did automatically put some channels on the card, I can't believe it could fill 4GB in the 3 or 4 seconds that message was on the screen.
Any ideas as to why a freshly formatted SD card would show 100% full?
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Update: apparently the SD card had become write protected, even though it allowed both the PC and the Roku to format it. I tried all the remedies Google suggested and nothing worked. I put in a 8GB SD card and it shows only 6% full.