fast finch
I don't currently have a screenshot, or video of this right now (but could produce one tonight) but, if you are holding some tracks and the white outline appears on the ground for you to place a new track at the end of the currently built track - then the game will not pick up additional tracks from the ground, even if you are not holding your maximum stack size limit.
This happens to me very often.
It causes some QOL problems while placing tracks: ex. while placing I could be holding a single track, but if I'm at the end of the track, even if there are entire stacks of tracks nearby, it will not automatically add them to my hands. I'd have to place the single track and pick up more tracks even though I was standing on a pile of them.
It also causes problems when trying to throwing tracks: ex. If I am throwing tracks near the end of the current track, after I throw some tracks, it will not automatically pick up additional tracks from the ground for me to continue throwing them and I end up needing to manually pick up more tracks even though I'm standing right on top them.
This bug only happens while the game is suggesting track placement for some reason.