Hi Dora,
Indeed, there seems to be an issue.
@lveci , @jun_lu you you have a look?.
Also at this post?
Batch processing tool - s1tbx - STEP Forum (esa.int)
As a workaround you could try using the command line.
There is a guide in our wiki on how to do it.
Bulk Processing with GPT - SNAP - Confluence (atlassian.net)