It's not a new phenomenon- has been reported before.
I tried to evaluate it hole-by-hole and came to some interesting observations:
If you check the stats immediately after the drive, they have a diverging state:
- FW hits on the scorecard will be updated if you hit FW (check mark) but not if you miss it (no dash).
- Accuracy %% will not be updated at this point. Thus, if you hit the first FW, the value will be zero. If you miss the second FW, the value will be 100% from hole one. This is updated only after you finished the hole, together with the dash.
I didn't finish the game because a mistake @4 would lead me into the rough, but I see some chance that the calculation at the last hole might be jumbled, omitting a value for the calculation.
Just a guess.