I am unable to access/explore the filesystem of my Android device over USB and MTP. Upon either clicking the device in the left sidebar of Dolphin, or opening the device with the file manager from the device notifier, I am given an error, "Malformed URL". This otherwise works under Solus, Solus GNOME, and Solus MATE.
There seems to be a problem with the newer kernels and KDE's 'Solid' backend. There's a bug report here about it.
I don't even get the malformed URL error, instead I get an uri one. When I run mtp-detect in a terminal, the phone is there. When I run solid-hardware5 list it's not. Unless solid sees it, kio doesn't know what to do with it.
If you have wifi you can use kde-connect as a workaround. Hopefully upstream will get mtp sorted out soon.
I've gone ahead with the LTS kernel and it seems this doesn't happen with it. It still acts a little weird, like the connection itself is unstable, despite me checking cables and both devices thoroughly, but it is working.
Works with LTS kernel, but as @Schyken said, it's intermittent. That's also a problem that was reported upstream back in 2013, with reports being added to the bug ticket right up to December of last year.
Seems to be a timing issue between detection/seeing if the device is still connected and KIO. Definitely upstream though.