Project Class Categories - Assign to all project types enabled and greyed out

Hi Experts - we want a class category to be enabled as accounting source but only applicable for certain project types.

Now when we check the "Available as accounting source" the 'Assign to all project types' flag is also being enabled automatically and greyed out.

Note that this is not the case before as we are able to make the category enabled as accounting source but not enabled for all project types.

Sample printscreen below

Any thoughts on the issue?