I am working on ArcgisPro 2.4.
I am working on the style of OS Master Map to create custom style, I added the style "Ordnance_Survey_en". Very often when I try to add new marker or customise older marker or symbol for a polygon feature, program starting to crash. It doesn't crash completely, however I can't do anything as it shows it's "thinking". I waited 30 min or longer few times and it's still the same. I can't save the project I can't access legend or symbology tab. Also I can't close the program without using a task manager.
Thank you for any help.