It ´s only a flaw. Really no big matter.
Today I did some test with automatic generated zfs-snapshots. There were 62 snapshots created overall, whereof only the first 25 are shown on one page in the ZFS snapshots tab.
So there are 3 pages at all. But the page counter shows " 1 of 1" page.
Only after switching to the next page the counter is updated to page "2 of 3".