Seems this one isn't reported yet...

When admin gives penalty with /p_dt or /p_sg, and driver doesn't cross split line before entering pitlane (i.e. penalty is given when car is between last split & pitlane entrance and driver goes to pitlane right away), LFS says "Entered pitlane for no purpose" and driver can't complete penalty.

My teammate had this in last MoE race and had to do two drive-throughs.