ADB Install seems to fail (preventing me from debugging on device using Visual Studio)

I use VS2015 with Xamarin to deploy an app to my phone. After recently rooting and wiping my phone data, I'm receiving errors upon deploying. The most common issue was that the "Fast deploy" was enabled, but I already had that turned off.

I figured out that my ADB Install seems to fail (permission denied), giving me the following error:

failed to copy 'x' to '/data/local/tmp/x': Permission denied

It really starts working on my nerves, and after trying several things which I found on the internet, I ended up asking a question here.

When I go to my 'ADB Shell' (running in root mode and showing this # sign), and type 'ls -ld data data/local data/local/tmp'

it shows the following, which seems to be normal (according to things I read): drwxrwx--x system system 2016-06-26 15:11 data drwxr-x--x root root 2016-06-26 08:52 local drwxrwx--x shell shell 2016-06-26 01:58 tmp

I started by recreating the 'tmp' folder, and using 'EF File Explorer' on my phone I can modify things and do everything I'd like to do. (modify rights, add folders, remove folders, recreate the folders and so on).

When I go to 'Root explorer' in EF File Explorer, I changed the '/' folder mode to 'RW', but it didn't make any change. Root explorer says it's still on "r/o" (read only) mode.

I tried the 'busybox mount -o remount, rw /system' trick and other mount-commands which did the trick for others, but still same issue with my phone. Furthermore, I tried a "move" trick in the shell, which didn't work out either.

As a last option I even tried to do a full format/wipe, but even thát did not solve my issue.

So I'm currently back at square one, where my 'ls -ld' is still showing the same information. Copying files to the internal storage via Windows Explorer works as it should.

Hopefully I'm doing something stupid and is there a fix for this issue. Thanks in advance for your help.