The String Synth seems to be missing its sound

I know its probably an underused feature, but in MS 4.3, the string synthesizer appears to have lost its MS basic audio patch (if that's the correct term?), instead playing the default piano sounds. I checked some other synths and they appear to have kept their sound, which is weird. Has this happened to anyone before, and is there any way to remedy this, do I have to wait for 4.3.1, is it possible to downgrade back to 4.2.1?

Thank you!