"Other" Storage dramatically increased after 8.4 upgrade

Hi Everyone,

I own an iPhone 5, 64 GB. Yesterday I updated to the latest iOS 8.4.

This is what happened: I've always had plenty of room to download anything on my iPhone, until yesterday.

Well, I had about 20 GB in my music library. After the upgrade I had only a few random artists left (?!?!!). Ok no big deal, I connected it to iTunes and tried to upload my entire library again...and then I noticed a huge shortage of storage!!

Now -with NO music at all- I have only 6 GB left, and iTunes shows a huge increase of the "Other" datas (40 GB!!)

If I sum up all apps space, photos and mail etc. it's about 20 GB. Storage says I have 50 GB used and 6 GB free only... ...

Any idea on how can I fix this and why this update messed up my entire phone?

It looks like the pre-8.4 music library ended up into the Other datas...does it makes sense???

Thanks for helping out