Replacing Legacy Workflows with BPM workflows

Hi Fellow Sugar-users from the Netherlands!

I have a question about the Legacy Workflows in SugarBPM. Maybe some of you have experienced the same thing as we have. 

We created a Legacy Workflow for notifications when calls are upcoming using these steps: 

https://support.sugarcrm.com/knowledge_base/workflows/notifying_users_of_upcoming_calls_and_meetings/#Creating_a_Workflow_Alert_Template

However, this has always worked well until 2 weeks ago. All the sudden my coworker stopped receiving the notifications.

I wonder if something has changed within Sugar that now prevents these notifications from going through and if anyone has experienced something similar? 

Currently most of our processes are running on Legacy Workflows, but I understood that they will soon fully be replaced with coming updates for Sugar BPM. 

I am looking forward to your answer(s)! Thank you in advance.

Best regards,

Maike