LG G3 (d855) Lollipop: cannot set custom ringtone I'm having a weird situation: I cannot add a custom ringtone to my LG G3.

I made an MP3 file with Audacity, I uploaded it using AirDroid and set it as default ringtone (like I used to do on my GT-I9300 with CyanogenMod) but it won't take it, when I receive a phone call the default LG ringt one is used.
But apparently everything is set up correctly, after setting the ringtone with AirDroid if I go on the phone settings I see the correct file seleced, not LG's one.
I tried playing the audio from there and it works.

To make sure it wasn't a problem with the mp3 file itself I tried:


cutting down the size of the file: from a full song (3M) I tried stripping it to something like 30s (1M)
changing format: the short file, saved as OGG instead of mp3
manually uploading in a different directory (instead of using AirDroid)


All tests have the same result: LG's ringtone! 

What works is using one of the other default ringtones provided by vendor. If I choose one of the existing tones the setting is correctly honored. 

I'm getting mad, I don't understand what I am doing wrong.
I'm now running the latest version available for my phone (V20h-EUR-XX). I had Android 4.4 for a week or two, and as far as I can remember (it wasn't my priority) this wasn't working with that version either.

I found a popular AE question about ringtones and Lollipop, but sadly I cannot find the Clear cached data option on my LG.
Thanks to the useful suggestion of a forum post I managed to fix by


copy the ringtone in the /Music~ folder (instead of/Ringtones`)
start the bundled music player, play the song I want for ringtone, then in the menu select Use as ringtone


This way I could finally change the ringtone with a custom one!