Internal display of Excel files

[LM7]

In the past, with the relevant settings for internal display of Office files activated (e.g. by double-clicking the Outlook.reg file), my Word and Excel files (I'm using Office 365, 32 bit edition) were displayed internally in UR (in both 32 bit edition and 64 bit edition), in both Win 10 and Win 11 (both 64 bit), with the most recent updates installed.

Recently, though, Excel files are no longer displayed internally in UR (on both OSes just mentioned), even though Word files are.

I reinstalled UR and tried Outlook.reg again, but to no avail.

Any ideas about why this might be happening, and how to solve it? (Might this be related to some sort of MS update of internal IE which is preventing the internal display in UR of Excel, in similar fashion to what happened some time ago with regard to the UR Outlook viewer?)

Thanks!