It may just be that the SQ1 can't process the data at the speed it is being transmitted by the software. I remember this being the case with some Roland synths receiving large sysex dumps. Smaller dumps tend to work simply because they don't push the MIDI receive hardware on the synth for too hard and too long. But longer dumps often eventually fail resulting in some data being corrupted which would cause the error you are seeing.

I don't use Cubase so can't tell you what to do to slow the transmission speed down a little. But your sysex file may be fine.