How doe one properly use the -I parameter ?

[acmehax]

I am quite new to gdu and am appreciating it quite a bit, good job ! However, I can't seem to get the -I or --ignore-dirs-pattern functionality working. I understand that this option looks for a regex term so I have tried a few iterations but w/o any success. For instance, on a Mac, I would like gdu to ignore the file .DS_Store AND any files that begin with ._.
However, I keep getting files that match these filters. I have tried gdu in these ways ...

gdu-go -naI ''.DS_Store|._.[\w]' /targetDir
gdu-go -na -I ''.DS_Store|._.[\w]' /targetDir
gdu-go -naI ''/targetDir/.DS_Store|/targetDir/._.[\w]' /targetDir
gdu-go -na -I ''/targetDir/.DS_Store|/targetDir/._.[\w]' /targetDir

Where /targetDir/ is the path within which I want gdu-go to run.

I tested to verify that the -i, --ignore-dirs requires a FULL/absolute path so I've tried -I, --ignore-dirs-pattern both with and without a full directory path. Is the -I, --ignore-dirs-pattern option pattern only good to ignore entire directories rather than individual files ? If so, this would be a shame :(

Thanks in advance for clarification.

S