Strange problem with cycled audio

[Botan]

I have an audio file, which cycled very well, so you can play it eternally with no lags. But when I change composition fps from 50 to 60 (or from 25 to 30 - the same effect), I can clearly hear a scratch in the end as if the cycle has been broken. This scratch takes place in final video as well. What can I do?

[Botan]

And yes, I have only one audio file in only one audio track, and it is not connected with any video in composition