Hello,
I think that you've broken the Ynos Mon national park in this edit:

9d8
<  -10676742 | Tirwedd Cenedlaethol Ynys Môn
83c82
< (80 rows)
---
> (79 rows)

If you check the relation in Josm's relation editor you can see there is a gap.
Best Regards,
Andy
