G'day precontact,
The 767 I was flying didn't have a Pegasus FMC. It tracked to the holding fix ok then turned well inside the outbound track and about halfway down the outbound leg turned towards the LNAV holding pattern and then flew around the magenta line. LNAV was annunciated all the time and the wind wasn't particularly strong.
It was just an odd looking pattern. The aircraft usually sticks closely to the magenta line.
Tanker driver are you?
Regards,
BH.