@ElzNicola I would like to take a look at the behavior you are encountering. Can you confirm what version of Designer you are using when encountering this issue? Also can you provide a sample workflow demonstrating the issue?
@ElzNicola Thanks for the update. I shouldn't need any of the data associated with the workflow, but the workflow itself would be helpful so I can try and reproduce the behavior. Since this appears to be sensitive you could provide the information via email. I can also provide a dropbox link to upload the file to if that would help, or if you have a preferred file service you can send me that information via email or private message.
In the mean time if you could confirm what version of Designer you are using I could try to reproduce the issue based on the description you have provided.