Hi guys it's been a while, but I'm back using Ubuntu Mate again and loving it (especially now it supports my AMD card now!). I'm using 18.04.2 and seem to be having trouble with connecting my samsung galaxy 3 in order to get pictures off my phone. I plug it in with my usb cable, give the ok when the phone asks if it can transfer files, then I see the phone link on the desktop. I open the folders, but when I get to the 'camera' folder-I cant see any pictures! Is there something I'm missing or is there a utility I can get to import my pics?
Hi
until you get a better reply.....my Android 8.1.0 works with existing UM 19.04 and Caja
but there is a stand alone package called android-file-transfer = AFT
you can try its about a 20Mb download
here were my steps and you can read about Appimage here
sudo apt install libappimage0
I used web browser to download the appimage file from link below
scrolll down and download v 3.9 Android_File_Transfer-803f53f-x86_64.AppImage
I am lazy so kept it in Downloads dir but you may want to move it?
make it executable
so pretending you are not sure and leave it in Downloads
cd Downloads
chmod +x Android_File_Transfer-803f53f-x86_64.AppImage
Now connect your phone and choose file transfer instead of charging
Next run the appimage by
./Android_File_Transfer-803f53f-x86_64.AppImage
You may get an error that MTP is already being used so for me I choose abort button to abort MTP for UM software then AFT works as expected
and so after abort is clicked AFT works
forum truncates image if interested view full image
I tested one image....so navigate to either internal storage or sdcard
-> DCIM -> nameofcameraapp (I use opencamera)
list of images should appear
I am a RH mouse user
RH click one image and choose Download
(its actually treating your phone like the internet not as an upload to PC)
Choose dir to download it too...
sorry if I confuse you with too much info 
use file manager to click on image to test its good.
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Adding a file to sdcard test
---unable to upload single file so upload my dir of Pictures from PC
click on sdcard
click on upload dir
(I chose Pictures)
Pictures was NOT a dir on my sdcard already
after transfer....I disconnected cable to confirm I still had Pictures dir on my PC
then re-enabled AFT to remove that dir from sdcard
Good luck