iCal calendar is static and does not update

Hello!

I have a question about the calendar in outlook.com. I work at a university, and they have a calendar that I can subscribe to with all the events and meetings that take place. For ages I have been using a special URL (iCal) in order to sync this calendar, that continuingly updates - sometimes meetings or lectures are cancelled or shifted, so it's not static. I use it on a lot of devices, on my private iPhone, on my Android phone for work as well as my work laptop running Ubuntu and it works without problems and always has. 

Now I got a Surface running Windows and was unable to find a possibility to add this kind of calendar directly to the Windows 10 calendar, but found out that it's possible to add the calendars (it's two in fact, one with all the public events, and one with my personal stuff that only concern me) to my calendar in my Microsoft account, and sync it to my Surface. So I added both of the calendars and voilà, they were on my Surface immediately. But there's one problem - it's completely static. If an appointment is added or something is cancelled, it does not appear or vanish on my calendar. It always stays the same and is completely useless for me. I read that it can take up to 24h to update, but I've waited 48 hours and nothing happened. As soon as I remove the calendar and add it again, the changes are made of course. On my other devices, changes update almost immediately...

My URLs look like this:

https://online.uni-****/kju_onlinej/ws/termin/ical?pStd=XXXXXXXXX&pToken=XXXXXXXXXXXXXXXXXXXXXXXXXXXX

I added the calendar by clicking "Add calendar", and then "subscribe from Internet".

Is there another way to subscribe to an iCal calendar, and does anybody know why it's not working for me? And just to be clear, I don't want to add the calendar to the Office program "Outlook". I'd really like to use the Windows 10 calendar, because it integrates nicely with Windows, and I can see my appointments by clicking on the clock in the bottom-right corner. 

For now I'm using Thunderbird where everything works fine, but I'd really like to use the built in Windows 10 calendar app.

Thanks in advance,

Kristian