It looks like the Panasonic file naming is not conform the standard as used by most other cameras. The standard is to use a directory structure as follows:
/DCIM/<A><B>/<C><D>.<E>
Where the subdirectory name is made up of
A = 3 digits for folder number starting with the number 100
B = 5 characters usually with an indication of the camera type
and the file name is made up of
C = 3 characters (default: DSC) plus an underscore either in front (adobe RGB) or at the end (sRGB)
D = 4 digits for the frame number
E = 3 character file name suffix (jpg for jpg, tif for tif, etc.)
From your post I gather that they actually name their files as follows:
P<A><D>.<E>
Where only three digits of <D> are used.
If instead of using {fnum} in your rename template you'd use {filenamebase:3,1}{filenamebase:5,3} (i.e., take 3rd and last three digits of the original filename) you will get what you want. Note: this only works on the original file names!
Hope this helps,
Hayo
