Hi, in my naming scheme I was using a counter with digits set to 2, and I was getting 01, 02, 03, 04, 05, just like I wanted.
But I tried to get smart and use track metadata for this instead, so I used @TrackIndex0X@ figuring it would give me the same thing. I got 1, 2, 3, 4, 5 (no leading 0).
So, I switched back to using a counter, but I thought it might be worth a bug report.
(Mac, Catalina 10.15.7, WL 10.0.70)