Instruments are not visible

Hi,
From page 28, I would like to continue with violin, bass viol and harpsichord by adding them to the voice but I can't see how to do it. I may have created the voice part from this point and in doing so, did something strange. Apologies. If you could take a look, I would be grateful. All the instruments appear to be in view in the layout but I can't see them in the score at this point. I'm using Musescore 4.5.1.2.