Unable to delete files nor to write excel files

I have 2 problems and they may be related to each other

I am an administrative user on my pc
It's on a home network
Always worked well till 3 weeks ago
When I want to delete a file, i am now always asked to give administrator rights
After giving the rights, I must confirm to delete
This was not the case before.

When I open a spreadshet with Excel, I get an error message when I want to save the changes.
It says there is a sharing violation and that it can only save to another file.
However, even this is not working.

When I use Planmaker I can edit and save these files
Planmaker is an excel clone

It is strange that MS-Word and Planmaker are not affected

I hope somebody can solve this

That sounds like an Excel issue, or possibly a Defender/Antivirus issue. How is Opus involved, other than being the thing which launches Excel?

If you're seeing errors when doing things in Excel, this is the wrong place to ask about that.

Oeps Leo, I forgot to tell that this problem is not happening when I launch from Exploer

It'll either be antivirus doing something (if you're using Defender, that's causing problems for lots of people at the moment), or due to a thumbnailer or viewer component looking at the files and not releasing the locks. None of those things are things which Opus itself does, so the actual solution will be outside of Opus.

I would start with whitelisting Opus in all parts of Defender (virus scanner, protected folders, privacy guard), if that is what you're using. It may block programs launched from Opus from writing to your document files/folders, for example.