Stave lines disappear

I'm in Windows11 with an NVidia GeForce RTX 4060 Ti display adaptor. I'm work on a score with 2 flute parts, 2 oboe parts, 2 clarinet parts, 2 bassoon parts, 1 horn, 1 trumpet, 3 different trombone parts, a timpani and strings. The view setting is at 100%. For some reason, some staves have missing lines. When I move the score about, the missing stave effect occurs for random instruments.

Can I change a setting to make this stop happening? What am I doing wrong?