There does seem to be an issue here – cutaway score with bar numbers every bar shown above top staff. And the behavior is different depending on whether staves are coming or going.
Here the second staff becomes the top staff in bar 62, but it also gains a bar number for bar 61 (and every previous bar on that system, not shown in this image). On the next page, that staff doesn’t get a bar number for 64 even though it’s the top staff at that point. And no staff has a bar number for 68.