[SCREEN CUSTOMIZATION] Issue with mandatory fields

Hello,

I am experiencing an issue with the definition of mandatory fields in the 'Activity' element. 
I would like to make some fields mandatory at specific state of the Activity. 

No problem with making mandatory a field on the whole Activity worlflow (by clicking on the pen). 

My problem appears when I want to be more accurate and I make a field mandatory at a specific state of the activity. 
The feature works fine with the 5 fields at the top of the list but it doesnt work anymore with any fields being positioned below these 5. 

It seems like the system is unable to save the parameters I apply. Each time I try to save manually my changes, the system either doesnt detect any changes either refresh the changes i made below this 5th fields (underlined in yellow in the attachment)

Do you have any idea what cause this issue and how to solve it ? The hosting server has been restarted with all relevant services. ProjeQtor version is 11.3.1 (not possible to update at the moment). 

Thank you very much for your help.