LMS not registering course completion for a few employees.

Hello all

I apologise if this has been answered before. I have created many courses using Captivate 2019 but sometimes I receive a query where an empoyee has passed a course (we have quiz's on each course with a pass rate of 80%) but this has not regiesterd with the LMS which is SAP Success Factors.  1 course has been completed by over 150 people, yet 2 others have this problem ?  I have asked that they use Chrome, delete there cache and ensure that they use the X button at the bottom of the screen to close the training.   Am I missing anything else that I can ask them to try ??

Many regards

Andy Chamberlain