Why don't hoppers behave properly?

I'm trying to build a sorting machine but can't make it work now.

It was working when I built it, but after a couple of days it broke!

The hoppers are supposed to be locked until they have 18 blocks in them, but now they tick immediately with only 1

 

Explain please. That's a bit too cryptic for me. ;-)

 

Having read earlier posts found in google searches, I have the following set in spigot.yml...

hopper-alt-ticking: true
ticks-per:
hopper-transfer: 8
hopper-check: 1

But things still don't work vanilla!