Volume mounting does not work properly on VBox (Windows)

I'm running docker on a Windows 7 x64 machine.
Docker: Docker version 1.11.2, build b9f10c9
VirtualBox: 5.1.2

Working in a folder with a file `Hello.txt`, I start the Docker Quickstart terminal:

```
$ cat Hello.txt
Hello world, how are you?
```

I use the following command to start a docker image and check the file is present:

```
$ docker run --rm -it --volume=$(pwd):/folder alpine /bin/sh
/ # cd folder
/folder # cat Hello.txt
Hello world, how are you?/folder #
```

Now I change the file through windows (Notepad++) so it has the following content: `Great!` and try again in the docker:

```
/folder # cat Hello.txt
Hello /folder #
```

It gets even stranger when changing the file from within docker:

```
/folder # echo Strange! > Hello.txt
/folder # cat Hello.txt
Hello wor/folder #
```

Restarting the docker image doesn't have any effect (it still shows the incorrect file content), after restarting the VM and starting a new docker image, the correct content is shown. This made me think of a bug in VirtualBox, but in an ubuntu image, this problem does not occur:
`docker run --rm -it --volume=$(pwd):/folder ubuntu:14.04 /bin/sh`
(Though the `sh` seems to be of a different version there.)