We have a process that uses a VERY big form (more than 1000 fields and lot of custom JS).

Some of the forms (not all) are getting stuck after submission. I checked in the Form's Results, and around 10% of forms are getting stuck. When I re-run them, they submit and come to repository with no issues.

I checked the logs and I don't see any issue during the time it shows the form got stuck. 

Please let me know what can be the reason for this. I am not sure if I am looking at the right place for the logs. Please let me know if I need to look at somewhere else to identify the real problem. 

Please see screenshots below.