Hello detroit123,
You are correct to a point. My observation here is that the .RW2 files import successfully, but do not display correctly. Given that the Panasonic GH6 was only recently released (March 22), it's perhaps understandable that PhD hasn't been adapted/patched to correctly deal with these files.
I downloaded some sample files from the GH6 from
Photography Blog & the RW2 displayed as shown below, in both PhD 365 & PhD 13:
I'm sure the team at CyberLink would be aware of this issue, but I'll alert them anyway.
PIX
PIX YouTube channel