Drive P: may be a mapped network drive, but drive mappings are a Windows construct, and the linux workers know nothing about them.
Qube has path translation, but it can only translate the paths present at the command-line. It can't translate the reference paths in the maya scene file.
You can either experiment with the Maya 'dirmap' command and express the path translation inside maya, or you can keep reading a get a couple of hints on how to take a sys-admin approach to side-stepping this problem.
You need to express the paths to the references inside Maya in a format that works on both the Windows and linux hosts so that no path translation is necessary.
If you use UNC paths on the Windows side, you're most of the way to getting this working. Then you only need to create a symlink on the linux side, combined with some NFS mount, to have the UNC path look like a valid NFS path on the linux side.
Say the UNC path that P: drive currently maps to looks like:
\\server1\shareName
on the linux side, you would create the mount point
mkdir -p /mnt/server1
and NFS-mount the same share something like this (refer to the documentation specific to your OS for the exact details):
mount.nfs server1:/shareName /mnt/server1/shareName
and in the root of the linux drive, create a symlink:
ln -s /mnt/server1 /server1
Then test the symlink using the UNC-style path (but with the slashes pointing the unix-correct way):
ls //server1/shareName
This should list the contents of the network share.
Re-save your Maya scene with UNC paths for the reference files, then submit another render job. The paths should then resolve correctly.