Description
Rapid pulse is not received if the redstone dust's length/strength is not further that 3 blocks

Steps To Reproduce
1. Make a rapid pulse generator using the comparator.
2. Extend the comparator's output by 1 (redstone dust).
3. Place a command block and write this command: "say Hi" (basically it has to be a command that can be output as text from the command block).
4. You can see that the command block's message is only output once.
5. Now, remove the command block one block further
6. Place one redstone dust to connect the rapid pulse generator's output with the command block.
7. Now the message is being output rapidly, as expected.
(More details in the screenshots)