This is an old question, but if anyone else runs into this problem in the future . . .
@camba1's answer is close, but not correct.
Theoretically, your code should work as it is, and there should not be a need for a redundant COPY INTO command.
My best guess, since you are using the chown flag in your COPY INTO command, is that there is a file permission issue with accessing the data as the node user/group without the COPY INTO explicitly setting the R/W/X permissions/ownership.
To quickly test this, you could try to lower the permissions (safely and for debugging only) on the bound directories directly so that the node user may access them.