Versions:
-Minecraft Forge: 14.23.5.2847
-Industrial Renewal: 0.21.6

What happens:
The powered rails from this mod do not accelerate stationary carts

What should happen:
"accelerate a non-moving minecart away from a solid opaque block the powered rail is facing (so a non-moving minecart moves away from the block when the powered rail activates, and a moving minecart bounces off a block an active powered rail is facing because it stops and then gets accelerated away)" - Minecraft Wiki