Why is the Costume Ringtone Short

[Windows Central Question]

I have downloaded my ringtones from my android device to the Ringtone Folder, they are all MP3 format, then when i choose those ringtones they are very short in duration if the ring tone is for lets say 30 Seconds it goes on for 10 or 15 secs then it stops. i tried to download and install ring tone maker and edited the ring tones hoping that it fixed the issue, yet its the same nothing changed, could you please help me out with this problem?