How to reproduce:
1. Open the "SampleScene_Track" scene in the attached "Bumper Cars Prototype 001.zip" project
2. Change the x coordinate to 0 on Playfield > Obstacle001
3. Constrain x Position and z Rotation on PlayerCar's RigidBody
4. Enter Play Mode
5. Press "w" or up arrow to move the PlayerCar until you reach the yellow obstacle

Expected Behavior: The PlayerCar collides with the obstacle
Actual Behavior: The PlayerCar moves through the obstacle like it is not there

Reproducible with: 2017.4.19f1, 2018.3.3f1, 2019.1.0b1, 2019.2.0a2

Note: Collision Events are called, but no collision happens. Both GameObjects must have equal x coordinates(it happens even when x is not 0). If you uncheck the constraints on the PlayerCar and do the same you will see that the PlayerCar collides with the obstacle but has a slight x Coordinate translation and the Rotation changes. The issue seems to only happen between Capsule and Circle Colliders.

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fixed in: 2018.3.5f1, 2019.1.0b3, 2019.2.0a5