SharePoint Online Calendar Web part only shows events when in Edit Mode

Question

I have a calendar web part on a site that should show the absence of colleagues, however, on the page none of the entered absences is shown.

When I click Edit in the top right corner to view the page with the calendar in Edit Mode the absences are filled out. Also, in normal view I can't switch between months, add events, ... While in Edit Mode this is possible.

I have already tried deleting the web part and recreating it (both on the same site as on another) but the issue still continues. Does anyone know why this happens and, if so, how I could resolve this?

I added screenshots of the calendar below, at the bottom of the message.

If there is any other information you need or you have any other questions, please don't hesitate to ask!

Thanks in advance!

EDIT 1

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Screenshot of the console in normal view, in Edit mode the error isn't there:

I have also noticed, thanks to this post, that on IE this issue does not occur, but I would like for it to work in Chrome as well but I don't know how to create a new Web Part Zone and I can't find any documentation that shows how to do this without SP Designer. I don't have SP Designer available so if it's possible to create one without it please elaborate on how I would be able to achieve this. If it's necessary to have SP Designer, how do I figure out which version to install? (This part of the question will be removed after I know the answer because it's not relevant to the issue described in the title)