Affricate sounds [ts, dz, tʃ, dʒ] are heard when sibilant sounds /s, z, ʃ, ʒ/ precede /n/. If /t, d/ precede /i/ then they are realized as affricates [tʃ, dʒ].
/n/ before /i/ may be realized as a palatal [ɲ].[2]
References
^Kogi at Ethnologue (18th ed., 2015) (subscription required)
^ abGawthorne, Linda A.; Hensarling, Grace E. (1984). Fonología del cogui. Sistemas fonológicos de idiomas colombianos (V.G.Waterhouse, comp.): Lomalinda: Editorial Townsend.