Composite interface not saving the annotations

[guglielmoacabbi]

I'm currently running the tool on my machine using the suggested docker command docker run -p 3000:3000 -p 3001:3001 \ -e UDT_collaborationServer_url=http://localhost:3001 \ universaldatatool/universaldatatool.
I created a composite task with two different Named entity recognition tasks and a couple of sentences as samples. I tried to annotate them but I am not able to save the annotations in any way. My steps are:

1. Click on the left menu on Label
2. Select the first sample
3. Select either of the two named entity recognition task
4. Annotate
5. Click on the Save button in the upper right corner

But then, if I reopen the task I just annotated, I cannot see my annotations. I tried to change step 5 by clicking on the next button, but the result is the same. I cannot find a way to save my annotations.