Hi FlameHs,
I'm Sumit, here to answer your query at the Microsoft Community.
Apologies for any inconvenience you are experiencing. I am happy to help you today.
I am not sure if it is a bug or some design change. Let us verify that.
Please download https://aka.ms/EdgeInsider and use the Dev version. Let me know if the breakpoints appear in that. If they do, file a bug report from Retail version of Edge, using ALT+SHIFT+I buttons.
I look forward to your response and am eager to collaborate until we find a solution.