I just copied an apk in my USB Drive, then inserted it into my android TV. And I found it write some files in my USB drive during installing. After I removed the USB Drive, it refuses to install from App Store now, it says, there is not enough space (I'm pretty sure there is).
I guess it regard my USB Drive as external storage now. Any way to resolve this?
If you setup that USB drive as an internal storage and then you remove it, the OS will still take that as the default location for installing apps even if you remove it, if you don't want to keep using it, you must remove it from the storage section, you'll see it's still there as if you had it plugged.
I always install using Send Files To TV, takes seconds and saves all the hassle of USB drives
I don't think these things are related. You're just out of space. You can't install anything from the play store until that's resolved