CRUD for attachments not working as expected

Hi Community,

We've implemented CRUD model for attachments following indications on this post:

https://community.creatio.com/questions/best-practices-implementing-crud-model-attachments

Create Update and Delete rights are removed via business process at a certain stage.

Delete is working properly:

Update is the problem, as the user gets an error message:

but the file is anyhow inserted via drag and drop features

Anyone experience the same problem and found a way to fix this? 

This is a major issue for our customer as we are talking about very sensitive records where we need full control over at what stage we can add attachments

Thanks,

Luis