Error 540

Suddenly, from one day to another, I keep getting that annoying Error 540
whenever I try to get the cell value from another spreadsheet document.

First I open a spreadsheet document. The folder where the file is located
is included in Tools → Options … → Security → Macro Security … → Trusted
Sources → Trusted File Locations

Tools → Options … → Security → Options … → ☐ Block any links from documents
not among the trusted locations (see macro Security) is NOT checked.

Now I hit the New button to create a new spreadsheet file. I click cell A1
in that new spreadsheet, and I type ”=”, then I click cell L111 in the
other spreadsheet, the one I opened first. I then hit Enter.

A1 is now displaying ”Err:540”.

What am I expected to do to never see that happening again?

Err:540 means: ”*Happens if a function that requires (re)loading of
external sources is encountered and the user hasn't confirmed reloading of
external sources yet*”

No question whether I want to confirm reloading of anything came up, so
what am I supposed to do?

I had the same problem a few days ago and somehow it suddenly worked, but I
don't know what I did to make that happen, and not it doesn't seem to
matter what I do.

Do I also need to save the new spreadsheet file at some place included in
that Trusted File Locations?

LibreOffice 6.4.5
Manjaro Linux 20.0.3

Kind regards

Johnny Rosenberg