From Guild Docs – Runs:
Runs serve as a unit of reproducibility .
For that reason each time you do guild run it copies your code under a run directory made specifically for that run before guild runs the code.
Gulid does this for example so that you have a snapshot of the adhoc code that resulted e.g. in some nice results and you can actually go back to this code and see what you did there.
This run directory becomes the working directory your script will resolve all relative paths to. And since you haven’t told guild to also copy there the train data and the path you specified is relative, the train data are simply not there.
You can either specify the train data as an absolute path just to try if that works. But I would suggest to include your train data in the guild ecosystem somehow as well. At least as a project file dependency or probably rather as a run file dependency as your train data perhaps are result as some prepare-train-data operation, aren’t they?
Maybe you could go through the dependencies example to get a better understanding of how they work.