Momcozy bottle washer not draining completely

[u/Calm-Storm2502]

We used the Momcozy bottle washer for our first child and stored it away about a year ago. We got it out again for our second child and now when the cycle is finished there is about a half inch to an inch of water just sitting in the main tank. I've tried descaling with vinegar and water, I've taken all of the parts out and cleaned them, and have removed the internal filter and cleaned that. I've also cleaned the drainage hose and have tried to clean out the drainage hole as best as I could. Anyone else have this issue and a solution? TIA!