Sounds strange, have you tried a different SD card? Upgrading from a different build? My build machine did run out of space when compressing the RPi2 .img so I compressed it manually. The image should be fine though, but if it wasn't the .tar should work.Can someone else confirm?
Only have one sd but it works well with the libreelec alpha 7.90.0.10. I only do fresh install with dd using the .img (like I do with raspbian, retropie and so on ).
I download the tar, but I don't know yet what to do with it. I'll look and try.