Default SD card problem

I have Sandisk ultra microSD card class 10, 32 GB. When I download something through browser, or when I take pictures, they're automatically saved to SD card. But when I try to copy something to SD card with file explorer I can't, because the card behaves like it's read-only. Any way to fix this without formatting?

EDIT: When I connect the phone to pc, file transfer with Windows file explorer works. Just the file manager on the phone doesn't. https://play.google.com/store/apps/d...ft.fm.hd&hl=hr

Thank you