Observer block can't detect moving objects using redstone comparator

In which version of the game are you?

1.14.1 version it seems that Observe block can't detect an object using redstone comparator.

I wanted to use item frame and arrow with redstone comparator. But it doesn't detect by the observer block.

Can you fix this problem

the comparator doesn't give a block update, it just changes state. to make this work, build a 1-tick pulse and connect the comparator to that.