Wool farm stopped working

I have had a wool farm in my realm for years, and while I can’t tell you when exactly it stopped working, I believe it was about a year ago.

Things I’ve tried:

-Replaced the observer

-Replaced the dispenser

-The grass is still regrowing and I’ve sat and watch the sheep eat the grass after every “fix” and still nothing.

-The dispenser only works when manually triggered.

-wool is still being collected just fine when the dispenser is manually triggered

I’ve included some picture for reference.