Strange behaviour with replicate

I have a problem I do not understand. I have an app that runs this code:

 `${this.urlLocalDb}_replicate`, {source: '', target: 'db', websocket:true, continuous: true}).subscribe((data)=>{
             console.log('replicate server to -> source', data);
             this.ready = true;

After this, if I read localhost/db/_changes?include_docs=true I receive one document.
This document is not present on sync gateway [remoteserver/_all_docs].
On sync gateway I have deleted all documents, also there aren’t any elements in the admin panel.
I have removed documents server side with:

deleteProduct(id, rev) {
return this.http.delete(${id}?rev=${rev})
.map(res => {
return res.json();
.catch(error => {
return Observable.throw(error.json());

How can it happen?

What software are you using?