Realtime Preview makes rulers and objects disappear when moving
In Illustrator 24.1 the real time editing feature makes guides or other objects that have no fill or stroke or an object with a white fill and no stroke disappear when moved.
Luís Camacho commented
I came here to post exactly about this. Objects without fill and stroke are invisible during moves.
As for white objects without strokes, they're not really invisible, but since they're a fully white object against a fully white page you can't see them while moving... but you'll see them if they go over a coloured area such as the slug.
The attached video shows both issues happening. The solution for this is simple, while dragging an object the edges should always be visible.