I noticed this,
changing settings for the Filters at the bottom of the Junk email page sometimes don't 'stick'
when you change a setting a 'save' dialogue box should open which you click on to save the new setting,
I was trying to change the setting; General>Privacy & Data>External images, there are two options, I wanted the one " Always use the Outlook service to load images"
initially trying to change that setting wouldn't trigger a save dialogue box to appear and the setting change would never stick,
I came back to it recently and it seemed to have set itself!
so persist, maybe it takes a while for the updated setting to reach it's destination on the server, I've stuck to these two individual settings,
https://outlook.live.com/mail/0/options/general/export External images: Always use the Outlook service to load images
https://outlook.live.com/mail/0/options/mail/junkEmail Filters: Block attachments, pictures and links not in may Safe senders and domains list
the other thing I noticed was even after deleting all drafts, sent messages and deleted items, they still lurk in a 'recover items deleted from this folder' folder at the top of the deleted items folder,
click on that coloured text and it opens another folder you can empty entirely,
I must have purged hundreds of items from my account and the amount of storage on the Cloud reduced noticably,
if you have huge numbers of things saved in this folder it can take several minutes for them to be deleted, just be patient or do blocks of 50 at a time,
so yeah, there is a time lag between changing settings and deleting stuff, you have to allow the MS servers a bit of time to work through it all and keep persisting, going back the next day and seeing if your setting have stuck, re apply as necessary,