Volumes: Invalid mount path

Hey there!

So I’ve recently started using Docker and I got it all working. However, a couple of days ago I decided to rework my volumes and how I would install my app’s dependecies and I’ve hit a little snag now.
I always get something like this for my main service volumes when I do docker-compose up:
ERROR: for <service> Cannot create container for service <service>: b'invalid volume specification: \'<a ton of numbers and letters>:<volume>:rw\': invalid mount config for type "volume": invalid mount path: \'<volume>\' mount path must be absolute'
The thing is. I use abs paths in everything… At least I’d swear I am. I cannot figure out where this error occurs. I just know that I can build the image with no issue…

OS: Raspbian GNU/Linux 9 (stretch)

Docker version: Version: 18.06.1-ce
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​API version: 1.38
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​Go version: go1.10.3
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​Git commit: e68fc7a

Steps to reproduce: here’s a paste (all files are included there)

If you need anything more just tell me!

Thanks in advance!