Just noticed connectivity errors over IPv6. Checking our routing table showed that the cause was a completely missing Bytemark prefix. The prefix came back after a while, via AS3257.
Checking grh.sixxs.net showed only ~85 paths while the prefix was missing in our table, so I assume we are not alone. grh.sixxs.net currently shows 105 paths, which I believe is the expected result (same as other well connected sites):
grh.sixxs.net> show bgp 2001:41c8::/32
BGP routing table entry for 2001:41c8::/32
Paths: (105 available, best #89, table Default-IP-Routing-Table)
Known issue? Fixed now?