In my leap most USBs get mounted very slowly,
For example it takes more than 1:30 min for my 16GB USB3 flash drive to get mounted.
PS1: some USBs get mounted in a sec, eg. my 2GB USB2 flash drive.
PS2: some of them are FAT and some NTFS, and non has any problem in my Windows and Mageia linux,
Sorry, i got a new issue,
I just found out that usb drives with storage more than 16GB take some minutes to get mounted.
My 16GB SiliconPower gets about 3 minutes to get mounted, my 32GB seems never to get recognized (as i waited about 5~6 minutes without any success )