Not all water bottles flowing into brewing stands from hoppers

Only the first 3 water bottles are flowing into brewing stands. The hopper then seems to be locked (enabled: false - although it says it is enabled: true) after the first 3 water bottles have moved out of it into the brewing stand. So when there is space in the brewing stand for more water bottles to move into it they don't
https://gyazo.com/b69d0b6b0a7aa71bd72362542d27e11b - Hopper not locked
https://gyazo.com/7c63c1461bb504f499e4c6f5510bc512 - Top hopper full of water bottles
https://gyazo.com/5cd18c2e61b78f4cc0346f35d8a67705 - Ample water bottles. Top chest full also
https://gyazo.com/c6e18cc7ecd1c8118cfe8f3d24cd61fd - Lamps showing items present
https://gyazo.com/57c16df5b49023ed17da21892eb3d8f4 - Yet empty brewing stand
https://gyazo.com/8f148905d77305d4a5478ba6add7419a - However first 3 bottles travel down perfectly fine

What I expected to happen was...:
Water bottles to move into the brewing stand from the hopper when there is space in the brewing stand and the hopper isn't locked

What actually happened was...:
The hopper fails to transfer the water bottles through to the brewing stand

Steps to Reproduce:
1. Recreate images above