For some reason my graph is returning SMILES for aromatic groups that uses aromatic bond symbols e.g. NC:1:N:N:C:[N]1N.

RDKit does not recognize these symbols and it removes all the aromaticity to produce NC1NNCN1N, and openbabel produces the same result.

Some have speculated that its a smarts string

https://mattermodeling.stackexchange.com/questions/4981/how-to-canonicalize-smiles-written-with-aromatic-bond-symbols

others just say it's wrong.

openbabel/openbabel#2368

Do you know what is going on?

Thanks for your help!