No route to some AS nets from AS3320 (DTAG)

[Marco Moock]

Hello!

During some tests I noticed that some As aren't reachable from AS3320,
but from other AS they are. On the destination AS some systems also
reply and are productive systems.

This affects time.nist.gov - a well-known NTP service.
If affects more, but I will start with that.

2610:20:6f97:97::4
AS49 US National Institute of Standards & Technology

I also did a RIPE atlas measurement that confirmed the destination is
reachable from many other ISPs, but not from AS3320.
https://atlas.ripe.net/measurements/70072736/#probes

When using their looking glass, there is no route to the net
2610:20::/32.

https://lg.telekom.com/?queryTerm=*%2049&queryType=AsPathQuery&selectedVantagePoints=%5B%22Berlin%2C%20Germany%22%5D

HE's BGP toolkit shows that the net isn't listed in IRR nor RPKI signed.
https://bgp.he.net/AS49#_prefixes6

Is that maybe the reason the net isn't in their routing table?

-- 
kind regards
Marco