Hey Alastes, as the others have said, if you can give us more information we can look into it.

Heres the forum thread about the claims getting overwritten, but without more information we wont know if you were part of that bug

[bug] Resolved. 752+ Claims got overwritten.

Unless you had all your claims in a densely populated area close to someone else? can you maybe post a link to the map aswell? you just go to the map, zoom in to the locations and you click the link icon bottom left, then you can copy/paste that link in here.